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Hernández A, Hoffman K, Reyes R, Fernández-Guasti A. Multiparity favors same-sex partner preference in male rats. Behav Brain Res 2024; 461:114842. [PMID: 38160811 DOI: 10.1016/j.bbr.2023.114842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/03/2024]
Abstract
Same-sex partner preference is present in many mammals, including rodents. Several possible causal factors have been proposed for the establishment of this preference. The Fraternal Birth Order effect refers to the observation that older brothers increase the probability of homosexuality in men, but no experiment has analyzed this possibility. In this study, partner preference (tested in a three compartments box) and female and male sexual behavior (studied in a cylindrical arena) were evaluated in young male rats (3 months) born to multiparous mothers that had 4-6 previous gestations and around 12 months of age. Control groups were young male rats born to primiparous young (4 months) or aged (12 months) mothers. In the partner preference test, the males born to multiparous dams spent less time interacting with the receptive female and more time interacting with the sexually active male, and a 39% exhibited same-sex partner preference. This high percentage seems related to multiparity of their mothers and not to maternal age, because the males born to primiparous aged females (12 months) showed a similar low proportion of same-sex partner preference than the males born to young (4 months) primiparous females (4%). In the sexual behavior tests, no male born of a multiparous dam and with same-sex preference ejaculated and 54% displayed proceptivity and lordosis. Present results suggest that the fraternal birth order effect may occur also in rats.
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Affiliation(s)
- Alejandra Hernández
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Coapa, CDMX, Mexico
| | - Kurt Hoffman
- Centro de Investigación en Reproducción Animal, Cinvestav-UAT, Tlaxcala, Mexico
| | - Rebeca Reyes
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Coapa, CDMX, Mexico
| | - Alonso Fernández-Guasti
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Coapa, CDMX, Mexico.
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2
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Raymond M, Turek D, Crochet PA. Testing Fraternal Birth Order Effects and Antagonistic Effects for Homosexual Men: Power Comparison of Various Methods. ARCHIVES OF SEXUAL BEHAVIOR 2024:10.1007/s10508-024-02820-w. [PMID: 38438815 DOI: 10.1007/s10508-024-02820-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 01/19/2024] [Accepted: 01/20/2024] [Indexed: 03/06/2024]
Abstract
Research on the biological determinants of male homosexual preference has long realized that the older brother effect (FBOE, i.e., a higher fraternal birth rank of homosexuals) and the antagonist effect (AE, i.e., more fertile women have a higher chance of having a homosexual son) can both generate family data where homosexual men have more siblings and more older siblings than heterosexual men. Various statistical approaches were proposed in the recent literature to evaluate whether the action of FBOE or AE could be discriminated from empirical data, by controlling for the other effect. Here, we used simulated data to formally compare all the approaches that we could find in the relevant literature for their ability to reject the null hypothesis in the presence of a specified alternative hypothesis (tests based on regression, Bayesian modeling, or contingency tables). When testing for the FBOE, the relative performance of the different tests was different depending on the specific function generating the older brother effect. Even if no tests were found to always perform better than the others, some tests performed systematically poorly, and some tests displayed a systematic high rate of type-I error. For testing the AE, the relative performance of the tests was generally not changed across all parameter values assayed, providing a clear ranking of the various proposed approaches. Pros and cons for each candidate test are discussed, taking into consideration power and the rate of type-I error but also practicability, the possibility to control for confounding variables, and to consider alternative hypotheses.
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Affiliation(s)
- Michel Raymond
- Institut des Sciences de l'Evolution, University of Montpellier, CNRS, EPHE, IRD, place E. Bataillon, 34095, Montpellier, France.
| | - Daniel Turek
- Department of Mathematics, Lafayette College, Easton, PA, USA
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3
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Hayman J, Fortune DW. Sexual Orientation in Twins: Evidence That Human Sexual Identity May Be Determined Five Days Following Fertilization. Cureus 2023; 15:e51346. [PMID: 38161549 PMCID: PMC10757681 DOI: 10.7759/cureus.51346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2023] [Indexed: 01/03/2024] Open
Abstract
Human same-sex sexual attraction has been recorded from the beginning of written history. It remains a controversial topic, but recent theories favor prenatal influences. A paradox is the occurrence of same-sex orientation in twins in that there is a higher level of concordance in monozygous twins compared to that in dizygous twins or non-twin siblings. If sexual orientation was entirely genetically determined monozygous twins would be expected to have identical sexual inclinations. Monozygous twins have twice the incidence of sexual concordance in comparison to dizygous twins but a third of these pairs have different sexual identities. An explanation for this disparity may lie in the time an embryo splits to form two separate fetuses. If splitting occurs early in twin development each twin may develop his or her own sexual identity; splitting occurring later results in twins that have the same sexual dispositions. A possible process for such determination may be in the mitochondria, with universal maternal inheritance of a proportion of normal functioning but alternate mitochondria. Variation in the distribution of these mitochondria in neural precursor cells becomes a mechanism for the development of intrinsic sexual orientation and for the spectrum of human sexual inclinations. The timing of embryonic splitting may be determined from the examination of fetal membranes, and the concept of early fetal sexual orientation is open to support or disproval.
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Affiliation(s)
- John Hayman
- Clinical Pathology, The University of Melbourne, Melbourne, AUS
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Burke FF, Hinks M, Salia S, Sparkes KM, Swift-Gallant A. Using Animal Models to Study the Interplay Between the Biodevelopmental Pathways Underlying Human Sexual Orientation. ARCHIVES OF SEXUAL BEHAVIOR 2023; 52:2979-2984. [PMID: 36477673 DOI: 10.1007/s10508-022-02499-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Affiliation(s)
- Francine F Burke
- Department of Psychology, Memorial University of Newfoundland, 230 Elizabeth Ave., St John's, NL, A1B 3X9, Canada
| | - Meagan Hinks
- Department of Psychology, Memorial University of Newfoundland, 230 Elizabeth Ave., St John's, NL, A1B 3X9, Canada
| | - Stephanie Salia
- Department of Psychology, Memorial University of Newfoundland, 230 Elizabeth Ave., St John's, NL, A1B 3X9, Canada
| | - Kerri M Sparkes
- Department of Psychology, Memorial University of Newfoundland, 230 Elizabeth Ave., St John's, NL, A1B 3X9, Canada
| | - Ashlyn Swift-Gallant
- Department of Psychology, Memorial University of Newfoundland, 230 Elizabeth Ave., St John's, NL, A1B 3X9, Canada.
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VanderLaan DP, Skorska MN, Peragine DE, Coome LA. Carving the Biodevelopment of Same-Sex Sexual Orientation at Its Joints. ARCHIVES OF SEXUAL BEHAVIOR 2023; 52:2939-2962. [PMID: 35960401 DOI: 10.1007/s10508-022-02360-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/30/2022] [Accepted: 06/04/2022] [Indexed: 06/15/2023]
Abstract
Sexual orientation is a core aspect of human experience and understanding its development is fundamental to psychology as a scientific discipline. Biological perspectives have played an important role in uncovering the processes that contribute to sexual orientation development. Research in this field has relied on a variety of populations, including community, clinical, and cross-cultural samples, and has commonly focused on female gynephilia (i.e., female sexual attraction to adult females) and male androphilia (i.e., male sexual attraction to adult males). Genetic, hormonal, and immunological processes all appear to influence sexual orientation. Consistent with biological perspectives, there are sexual orientation differences in brain development and evidence indicates that similar biological influences apply across cultures. An outstanding question in the field is whether the hypothesized biological influences are all part of the same process or represent different developmental pathways leading to same-sex sexual orientation. Some studies indicate that same-sex sexually oriented people can be divided into subgroups who likely experienced different biological influences. Consideration of gender expression in addition to sexual orientation might help delineate such subgroups. Thus, future research on the possible existence of such subgroups could prove to be valuable for uncovering the biological development of sexual orientation. Recommendations for such future research are discussed.
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Affiliation(s)
- Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada.
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | - Malvina N Skorska
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Diana E Peragine
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada
| | - Lindsay A Coome
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada
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6
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Vilsmeier JK, Kossmeier M, Voracek M, Tran US. The fraternal birth-order effect as a statistical artefact: convergent evidence from probability calculus, simulated data, and multiverse meta-analysis. PeerJ 2023; 11:e15623. [PMID: 37609443 PMCID: PMC10441532 DOI: 10.7717/peerj.15623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 06/01/2023] [Indexed: 08/24/2023] Open
Abstract
The fraternal-birth order effect (FBOE) is a research claim which states that each older brother increases the odds of homosexual orientation in men via an immunoreactivity process known as the maternal immune hypothesis. Importantly, older sisters supposedly either do not affect these odds, or affect them to a lesser extent. Consequently, the fraternal birth-order effect predicts that the association between the number of older brothers and homosexual orientation in men is greater in magnitude than any association between the number of older sisters and homosexual orientation. This difference in magnitude represents the main theoretical estimand of the FBOE. In addition, no comparable effects should be observable among homosexual vs heterosexual women. Here, we triangulate the empirical foundations of the FBOE from three distinct, informative perspectives, complementing each other: first, drawing on basic probability calculus, we deduce mathematically that the body of statistical evidence used to make inferences about the main theoretical estimand of the FBOE rests on incorrect statistical reasoning. In particular, we show that throughout the literature researchers ascribe to the false assumptions that effects of family size should be adjusted for and that this could be achieved through the use of ratio variables. Second, using a data-simulation approach, we demonstrate that by using currently recommended statistical practices, researchers are bound to frequently draw incorrect conclusions. And third, we re-examine the empirical evidence of the fraternal birth-order effect in men and women by using a novel specification-curve and multiverse approach to meta-analysis (64 male and 17 female samples, N = 2,778,998). When analyzed correctly, the specific association between the number of older brothers and homosexual orientation is small, heterogenous in magnitude, and apparently not specific to men. In addition, existing research evidence seems to be exaggerated by small-study effects.
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Affiliation(s)
- Johannes K. Vilsmeier
- Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria
| | - Michael Kossmeier
- Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria
| | - Martin Voracek
- Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria
| | - Ulrich S. Tran
- Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria
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Teichroeb JA, Fox SA, Samartino S, Wikberg EC, Sicotte P. Non-Reproductive Sexual Behavior in Wild White-Thighed Colobus Monkeys (Colobus vellerosus). ARCHIVES OF SEXUAL BEHAVIOR 2023; 52:2295-2301. [PMID: 36849676 DOI: 10.1007/s10508-023-02561-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Rare behaviors are often missing from published papers, hampering phylogenetic analyses. Here, we report, for the first time, masturbation and same-sex sexual behavior (SSB) in both male and female black-and-white colobus monkeys. We recorded these behaviors during 32 months of observation (1573 h of focal animal sampling) on Colobus vellerosus collected at the Boabeng-Fiema Monkey Sanctuary in Ghana. Males were observed masturbating and involved in SSB more than females. Subadult males were the age-sex class that engaged in both of these behaviors most often and a third of all SSB observed in young males occurred when they were forming an all-male band (AMB), which are temporally transient social groups in this species. Our data support that masturbation in males may be a sexual outlet for individuals that do not have a current sexual partner, while in females it may function in mate attraction by advertising receptivity. SSB may occur as an evolutionary byproduct but given the temporal clustering of observed events in males prior to AMB formation, our data best support the hypothesis that these behaviors facilitate male-male bonding (i.e., act as social glue). Within AMB's, males engage in coalitionary behavior to take over social groups containing females and strong bonds are important for success and later access to females, which could have selected for SSB in C. vellerosus.
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Affiliation(s)
- Julie A Teichroeb
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.
| | - Stephanie A Fox
- Department of Anthropology, The University of New Mexico, Albuquerque, NM, USA
| | - Shelby Samartino
- Department of Anthropology, University of Texas at San Antonio, San Antonio, TX, USA
| | - Eva C Wikberg
- Department of Anthropology, University of Texas at San Antonio, San Antonio, TX, USA
| | - Pascale Sicotte
- Department of Biology, Concordia University, Montréal, QC, Canada
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Johnson L, Lukert B. Science, Scripture, and Sexuality: The US United Methodist Church at Crossroads. JOURNAL OF RELIGION AND HEALTH 2023:10.1007/s10943-023-01806-7. [PMID: 37079172 PMCID: PMC10117265 DOI: 10.1007/s10943-023-01806-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/21/2023] [Indexed: 05/03/2023]
Abstract
During the past 50 years, medical and behavioral scientists have made great progress in understanding the variables which influence the development of sexual orientation, identity, and consequent behavior. In most instances, homosexuality is influenced by hormonal, genetic, and immunologic variables during fetal development, and the effects cannot usually be altered without consequence. The recent struggle within The United Methodist Church in the USA reflects the difficulty that society in general has with accepting homosexuality as part of the spectrum of sexuality. Hopefully, understanding the factors influencing sexual orientation will aid in reducing prejudice and eventually bring an end to the pain endured by the LGBTQ community, and the conflict within The United Methodist Church, a prototype of the struggle.
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Masullo G, Coppola M. Potential and limitations of digital ethnographic research: A case study on a web community. FRONTIERS IN SOCIOLOGY 2023; 7:1092181. [PMID: 36687011 PMCID: PMC9846540 DOI: 10.3389/fsoc.2022.1092181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
INTRODUCTION This work aims at transposing ethnographic research into digital contexts to probe its potential and limitations in a specific field of study: that of sexuality, particularly suited to ethnographic exploration. We chose as our case study a web community of Italian asexual people. As we shall see, this allowed us to simultaneously explore both the various techniques called into play in digital ethnography and the digital as a specific sphere within which sexuality takes on a very peculiar meaning. Digital sociality is paramount for the definition of imaginaries, meanings, and practices that could not be explored elsewhere. This is due to the implicit characteristics of the population studied, which does not find corresponding physical spaces of aggregation. METHODS The paper will present the research design using this specific case study to address some of the typical dilemmas that researchers face when following the digital ethnographic approach and will explore the research results as an example of the kind of analysis available with the information and data collected through this method. RESULTS AND DISCUSSION The conclusions will attempt to briefly outline the shortfalls and advantages of this method, considering its application to this specific field of study.
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Affiliation(s)
- Giuseppe Masullo
- Department of Human Sciences, Philosophy and Education, University of Salerno, Fisciano, Italy
| | - Marianna Coppola
- Department of Political and Communication Sciences, University of Salerno, Fisciano, Italy
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10
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Semenyna SW, Gómez Jiménez FR, Vasey PL. Confounds, Causality, and Sexual Orientation: The Implications of a Population-Level Study of Sibling Characteristics and Same-Sex Attraction. JOURNAL OF SEX RESEARCH 2022; 59:690-696. [PMID: 35040379 DOI: 10.1080/00224499.2021.1990199] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Representative samples, and especially population samples, are coveted sources of high-quality data in psychological science. In their recent article, Ablaza et al. (2021) used a population sample of marriages and registered partnerships in the Netherlands to examine the relationships between sibling characteristics and sexual orientation. We discuss the implications of this work for understanding the fraternal and sororal birth order effects on male and female same-sex attraction, and how both relate to maternal reproduction. The causal assumptions of these findings are explored, as well as the necessity of population-level data, and whether the data presented by Ablaza et al. are truly representative of the Dutch population.
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Affiliation(s)
| | | | - Paul L Vasey
- Department of Psychology, University of Lethbridge
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11
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Jain S, Rana M. Alternative Sexual Orientation in Humans: What Is Known and What Needs to Be Known Further. JOURNAL OF HOMOSEXUALITY 2022; 69:1004-1029. [PMID: 33788667 DOI: 10.1080/00918369.2021.1898805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Since the 20th century, multiple studies have linked the variations in human sexual orientation, from heterosexuality to bisexuality or homosexuality, to a wide range of biological factors. However, a clear mechanism that leads to the development of these variations has not been established yet. This review consolidates various comprehensive studies on the possible biological factors in the fields of genetics, epigenetics, uterine environment, hormones, neuroanatomy, and neurobiology that lead to these variations. One intriguing question that 'homosexuality phenotype' faces is its ability to avoid elimination by Darwinian selection. This review tries to explain why natural selection is not eliminating the genetic factors associated with homosexuality even at the cost of the evolutionary fitness of homosexual individuals. Studies supporting certain strong candidates for alternative sexual orientation (ASO) are highlighted, which can become new research avenues for investigators in this field. Further, a novel speculation is proposed that might be contributing to the development of variation in human sexuality.
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Affiliation(s)
- Sidhant Jain
- Department of Zoology, University of Delhi, Delhi, India
| | - Meenakshi Rana
- Department of Zoology, University of Delhi, Delhi, India
- Dyal Singh College, University of Delhi, Delhi, India
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12
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Attanasio M, Masedu F, Quattrini F, Pino MC, Vagnetti R, Valenti M, Mazza M. Are Autism Spectrum Disorder and Asexuality Connected? ARCHIVES OF SEXUAL BEHAVIOR 2022; 51:2091-2115. [PMID: 34779982 DOI: 10.1007/s10508-021-02177-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/10/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
Asexuality is a lack of sexual attraction to any gender. There is some evidence to suggest that many self-identified asexuals have a formal diagnosis of autism spectrum disorder which is characterized by deficits in social interaction and communication, as well as by restricted and repetitive interests and behaviors. Additionally, the literature shows that asexuality and lack of sexual attraction or low sexual interest is overrepresented in people with autism spectrum disorder compared with neurotypical samples. Nevertheless, no studies have been conducted to investigate the relationship between autism and asexuality in depth. We conducted a systematic review of the literature to examine whether asexuality and autism spectrum disorder are connected. We conclude that asexuality and autism share various aspects, such as a possible role of prenatal factors, reference to romantic dimensions of sexual attraction and sexual orientation, and non-partner-oriented sexual desire, but future research should explore and clarify this link.
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Affiliation(s)
- Margherita Attanasio
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy.
- Reference Centre for Autism of the Abruzzo Region, Local Health Unit ASL 1, L'Aquila, Italy.
| | - Francesco Masedu
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
| | - Fabrizio Quattrini
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
| | - Maria Chiara Pino
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
| | - Roberto Vagnetti
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
| | - Marco Valenti
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
- Reference Centre for Autism of the Abruzzo Region, Local Health Unit ASL 1, L'Aquila, Italy
| | - Monica Mazza
- Department of Applied Clinical Sciences and Biotechnology, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Località Coppito, Italy
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13
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Gómez Jiménez FR, Vasey PL. Facial Attractiveness of the Sisters of Istmo Zapotec Men and Muxes: Implications for the Evolution of Male Androphilia. JOURNAL OF SEX RESEARCH 2022; 59:354-359. [PMID: 34213985 DOI: 10.1080/00224499.2021.1943737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Research shows that the female relatives of androphilic (i.e., sexually attracted to adult males) males have more children than the female relatives of gynephilic (i.e., sexually attracted to adult females) males. The mechanisms by which this occurs are unclear. The hypergyny hypothesis suggests that the female relatives of androphilic males have elevated attractiveness which allows them to obtain male partners with higher socioeconomic status, which in turn, provide them with more resources to produce and sustain multiple offspring. We tested whether the female kin of male androphiles are characterized by elevated attractiveness compared to the female kin of male gynephiles. The research was conducted among the Istmo Zapotec from Oaxaca, Mexico, where androphilic males are recognized as a third gender, muxes. We recruited 115 gynephilic men who rated the facial attractiveness of 27 women with at least one muxe sibling and 27 women with only gynephilic male siblings (i.e., control sisters). The results showed that gynephilic men found the faces of control sisters more attractive than the faces of muxe sisters. This finding is inconsistent with the hypergyny hypothesis and suggests that elevated facial attractiveness is not the mechanism by which the female relatives of androphilic males achieve elevated reproduction.
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Affiliation(s)
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge
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14
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Skorska MN, Coome LA, Saokhieo P, Kaewthip O, Chariyalertsak S, VanderLaan DP. Handedness and Birth Order Among Heterosexual Men, Gay Men, and Sao Praphet Song in Northern Thailand. ARCHIVES OF SEXUAL BEHAVIOR 2020; 49:2431-2448. [PMID: 32623540 DOI: 10.1007/s10508-020-01774-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 06/10/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
Previous research has examined handedness and birth order to inform sexual orientation and gender identity/role expression development; however, sexual orientation and gender identity/role expression have rarely been disentangled to provide a more nuanced perspective. In Thailand, we investigated sexual orientation and gender identity simultaneously via comparison of 282 heterosexual men, 201 gay men, and 178 sao praphet song-i.e., androphilic, markedly feminine males recognized as a "third" gender. Handedness was examined as: extremely left-handed, moderately left-handed, ambidextrous, moderately right-handed, or extremely right-handed. Birth order was examined as numbers of older and younger brothers and sisters, by using Berglin's, fraternal, and sororal indices, and by examining the older brother odds ratio and sibling sex ratio. Compared with heterosexual men, gay men and sao praphet song were more likely to be extremely right-handed. Sao praphet song were also more likely to be extremely left-handed than heterosexual and gay men. Heterosexual men and sao praphet song had later sororal birth order compared with the expected Thai population value, suggesting stopping rules influenced when probands' mothers ceased having children. These findings provide new insights and replicate previous findings in a non-Western sample. Regarding handedness, in males, mechanisms related to extreme right-handedness likely influence the development of androphilia, whereas mechanisms related to both extreme right- and extreme left-handedness likely explain the combination of androphilia and feminine gender identity/role expression. Regarding birth order, similar to the conclusions of some prior research, stopping rules pose a challenge for testing the fraternal birth order effect.
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Affiliation(s)
- Malvina N Skorska
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, ON, L5L 1C6, Canada
| | - Lindsay A Coome
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, ON, L5L 1C6, Canada
| | - Pongpun Saokhieo
- Research Institute of Health Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Oranitcha Kaewthip
- Research Institute of Health Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Suwat Chariyalertsak
- Research Institute of Health Sciences, Chiang Mai University, Chiang Mai, Thailand
- Faculty of Public Health, Chiang Mai University, Chiang Mai, Thailand
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, ON, L5L 1C6, Canada.
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada.
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15
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Balthazart J. Sexual partner preference in animals and humans. Neurosci Biobehav Rev 2020; 115:34-47. [PMID: 32450091 PMCID: PMC7484171 DOI: 10.1016/j.neubiorev.2020.03.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/11/2020] [Accepted: 03/24/2020] [Indexed: 12/25/2022]
Abstract
Sex differences in brain and behavior of animals including humans result from an interaction between biological and environmental influences. This is also true for the differences between men and women concerning sexual orientation. Sexual differentiation is mediated by three groups of biological mechanisms: early actions of sex steroids, more direct actions of sex-specific genes not mediated by gonadal sex steroids and epigenetic mechanisms. Differential interactions with parents and conspecifics have additionally long-term influences on behavior. This presentation reviews available evidence indicating that these different mechanisms play a significant role in the control of sexual partner preference in animals and humans, in other words the homosexual versus heterosexual orientation. Clinical and epidemiological studies of phenotypically selected populations indicate that early actions of hormones and genetic factors clearly contribute to the determination of sexual orientation. The maternal embryonic environment also modifies the incidence of male homosexuality via immunological mechanisms. The relative contribution of each of these mechanisms remains however to be determined.
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16
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Hernández A, Olvera-Hernández S, Fernández-Guasti A. Lack of interaction between prenatal stress and prenatal letrozole to induce same-sex preference in male rats. Physiol Behav 2020; 224:113042. [PMID: 32619527 DOI: 10.1016/j.physbeh.2020.113042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/12/2020] [Accepted: 06/28/2020] [Indexed: 12/29/2022]
Abstract
Same-sex partner preference between males has been observed in all species in which this behavior has been studied. Disruption of brain estradiol synthesis during development has been proposed as one of the biological causes underlying this behavior in some mammals. In support of this possibility, perinatal administration of aromatase inhibitors (such as letrozole) to male rat pups, induces around half of them to have same-sex preference and female sexual behavior in adulthood. Another putative factor that modifies sex preference is prenatal stress. Several stress protocols, applied to the pregnant dam, cause some of the adult male progeny to have an increased male preference, a decreased preference for the female, and lordosis behavior. Interestingly, these effects of stress might be mediated by its inhibitory action on brain aromatase. The aim of the present study was to analyze a possible interaction between these two factors in male rats. Pregnant dams were exposed to one of the four treatments across gestation days 10-22 (G10-G22): 1) vehicle-treated non-stressed controls; 2) letrozole (0.56 µg/kg); 3) 30 min immobilization stress); 4) both letrozole and stress combined. The male offspring were tested in adulthood for partner preference in a three-chambered arena, where we also recorded the masculine and feminine sexual behaviors. One week later males were tested for masculine and feminine sexual behavior in cylindrical arenas where they interacted for 30 min with a receptive female and thereafter with a sexually active male for another 30 min. Letrozole, stress and their combination resulted in same-sex preference in 40, 31 and 50% of males, respectively, compared to 5% in the control group. In the sexual behavior tests, prenatal stress reduced the percentage of males displaying intromissions and ejaculation (impaired masculinization), while letrozole mainly increased lordosis (impaired defeminization). The males prenatally submitted to stress and treated with letrozole presented these behavioral features but did not differ from both treatments given independently. The results indicate that the changes induced by stress or the aromatase inhibition produced by letrozole only accounts for a shift in partner preference in around half of the males and that there was no interaction between these two factors.
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Affiliation(s)
- Alejandra Hernández
- Pharmacobiology Department. Center of Research and Advanced Studies of IPN (CINVESTAV), México
| | - Sandra Olvera-Hernández
- Medical and Psychology School, Autonomous University of Baja California, Tijuana, B.C., México
| | - Alonso Fernández-Guasti
- Pharmacobiology Department. Center of Research and Advanced Studies of IPN (CINVESTAV), México..
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17
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Gómez Jiménez FR, Semenyna SW, Vasey PL. The relationship between fraternal birth order and childhood sex‐atypical behavior among the Istmo Zapotec
muxes. Dev Psychobiol 2020; 62:792-803. [DOI: 10.1002/dev.21987] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 12/22/2022]
Affiliation(s)
| | - Scott W. Semenyna
- Department of Psychology University of Lethbridge Lethbridge Alberta Canada
| | - Paul L. Vasey
- Department of Psychology University of Lethbridge Lethbridge Alberta Canada
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18
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Bogaert AF, Skorska MN. A short review of biological research on the development of sexual orientation. Horm Behav 2020; 119:104659. [PMID: 31911036 DOI: 10.1016/j.yhbeh.2019.104659] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 11/15/2022]
Abstract
We review research supporting biological mechanisms in the development of sexual orientation. This research includes studies on neural correlates, prenatal hormones and related physical/behavioral correlates, genetics, and the fraternal birth order effect (FBOE). These studies, taken together, have provided substantial support for biological influences underlying the development of sexual orientation, but questions remain unanswered, including how biological mechanisms may differ in contributing to men's and women's sexual orientation development.
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Affiliation(s)
- Anthony F Bogaert
- Department of Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada; Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada.
| | - Malvina N Skorska
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada; Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, ON L5L 1C6, Canada.
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19
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Microbiota changes associated with ADNP deficiencies: rapid indicators for NAP (CP201) treatment of the ADNP syndrome and beyond. J Neural Transm (Vienna) 2020; 127:251-263. [PMID: 32072336 PMCID: PMC7035218 DOI: 10.1007/s00702-020-02155-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 01/20/2020] [Indexed: 12/31/2022]
Abstract
Activity-dependent neuroprotective protein (ADNP) and its protein snippet NAP (drug candidate CP201) regulate synapse formation and cognitive as well as behavioral functions, in part, through microtubule interaction. Given potential interactions between the microbiome and brain function, we now investigated the potential effects of the ADNP-deficient genotype, mimicking the ADNP syndrome on microbiota composition in the Adnp+/– mouse model. We have discovered a surprising robust sexually dichotomized Adnp genotype effect and correction by NAP (CP201) as follows. Most of the commensal bacterial microbiota tested were affected by the Adnp genotype and corrected by NAP treatment in a male sex-dependent manner. The following list includes all the bacterial groups tested—labeled in bold are male Adnp—genotype increased and corrected (decreased) by NAP. (1) Eubacteriaceae (EubV3), (2) Enterobacteriaceae (Entero), (3) Enterococcus genus (gEncocc), (4) Lactobacillus group (Lacto), (5) Bifidobacterium genus (BIF), (6) Bacteroides/Prevotella species (Bac), (7) Clostridium coccoides group (Coer), (8) Clostridium leptum group (Cluster IV, sgClep), and (9) Mouse intestinal Bacteroides (MIB). No similarities were found between males and females regarding sex- and genotype-dependent microbiota distributions. Furthermore, a female Adnp+/– genotype associated decrease (contrasting male increase) was observed in the Lactobacillus group (Lacto). Significant correlations were discovered between specific bacterial group loads and open-field behavior as well as social recognition behaviors. In summary, we discovered ADNP deficiency associated changes in commensal gut microbiota compositions, a sex-dependent biomarker for the ADNP syndrome and beyond. Strikingly, we discovered rapidly detected NAP (CP201) treatment-dependent biomarkers within the gut microbiota.
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20
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Lippa RA. Interest, Personality, and Sexual Traits That Distinguish Heterosexual, Bisexual, and Homosexual Individuals: Are There Two Dimensions That Underlie Variations in Sexual Orientation? ARCHIVES OF SEXUAL BEHAVIOR 2020; 49:607-622. [PMID: 31989410 DOI: 10.1007/s10508-020-01643-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
A diverse U.S. sample comprising 1437 men and 1474 women was assessed on sexual orientation, masculinity-femininity of occupational preferences (MF-Occ), self-ascribed masculinity-femininity (Self-MF), Big Five personality traits, sex drive, and sociosexuality (positive attitudes toward uncommitted sex). Discriminant analyses explored which traits best distinguished self-identified heterosexual, bisexual, and homosexual individuals within each sex. These analyses correctly classified the sexual orientation of 55% of men and 60% of women, which was substantially better than a chance rate (33%) of assigning participants to one of three groups. For men, MF-Occ and Self-MF distinguished heterosexual, bisexual, and gay men, with heterosexual men most gender typical, gay men most gender atypical, and bisexual men intermediate. Independently, higher sex drive, sociosexuality, and neuroticism and lower conscientiousness distinguished bisexual men from other groups. For women, gender-related interests and Self-MF distinguished lesbians from other groups, with lesbians most gender atypical. Independently, higher sociosexuality, sex drive, and Self-MF distinguished non-heterosexual from heterosexual women. These findings suggest that variations in self-reported sexual orientation may be conceptualized in terms of two broad underlying individual difference dimensions, which differ somewhat for men and women: one linked to gender typicality versus gender atypicality and the other linked to sex drive, sociosexuality, and various personality traits.
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Affiliation(s)
- Richard A Lippa
- Psychology Department, California State University, Fullerton, Fullerton, CA, 92836, USA.
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21
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Gómez Jiménez FR, Semenyna SW, Vasey PL. Offspring Production Among the Relatives of Istmo Zapotec Men and Muxes. ARCHIVES OF SEXUAL BEHAVIOR 2020; 49:581-594. [PMID: 31897830 DOI: 10.1007/s10508-019-01611-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/12/2019] [Accepted: 12/14/2019] [Indexed: 06/10/2023]
Abstract
Male androphilia (i.e., sexual attraction toward adult males) is influenced by biological factors, reliably occurs across diverse cultures, and has persisted over evolutionary time despite the fact that it reduces reproduction. One possible solution to this evolutionary paradox is the sexually antagonistic gene hypothesis (SAGH), which states that genes associated with male androphilia reduce reproduction when present in males but increase reproduction when present in their female relatives. The present study tested the SAGH among the Istmo Zapotec-a non-Euro-American culture in Oaxaca, Mexico, where transgender and cisgender androphilic males are known as muxe gunaa and muxe nguiiu, respectively. To test the SAGH, we compared offspring production by the biological relatives of muxe gunaa (n = 115), muxe nguiiu (n = 112), and gynephilic men (i.e., cisgender males who are sexually attracted to adult females; n = 171). The mothers and paternal aunts of muxe gunaa had higher offspring production than those of muxe nguiiu. Additionally, the relatives of muxe gunaa had more offspring than those of gynephilic men, whereas no such differences were found between the families of gynephilic men and muxe nguiiu. Elevated reproduction by the mothers and, particularly the aunts, of muxe gunaa is consistent with the SAGH. However, the absence of group differences between gynephilic men and muxe nguiiu, and the group differences between the two types of muxes are not predicted by the SAGH. This is the first study to demonstrate reproductive differences between kin of transgender and cisgender androphilic males within the same non-Euro-American culture.
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Affiliation(s)
- Francisco R Gómez Jiménez
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada.
| | - Scott W Semenyna
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
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22
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Skorska MN, Bogaert AF. Fraternal Birth Order, Only-Child Status, and Sibling Sex Ratio Related to Sexual Orientation in the Add Health Data: A Re-analysis and Extended Findings. ARCHIVES OF SEXUAL BEHAVIOR 2020; 49:557-573. [PMID: 31802291 PMCID: PMC8241527 DOI: 10.1007/s10508-019-01496-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 05/18/2023]
Abstract
The fraternal birth order (FBO) effect related to men's sexual orientation refers to the finding that the number of older brothers that a man has increases his chance of being androphilic. The FBO effect has generally been well replicated in diverse samples; one instance of non-replication was by Francis (2008) using Waves I and III of the Add Health data. We attempted to replicate the FBO effect in the Add Health data taking into account family size and other limitations of Francis' (2008) analyses. Also, we examined other sibling characteristics related to the FBO effect: sibling sex ratio and only-child status. We used two subsamples from Waves I (n = 20,745) and IV (n = 15,701) of the Add Health data, consisting of adolescents who were followed longitudinally from 1994 to 1995 until 2008. Wave I data were used to compute numbers of younger and older brothers and sisters from household roster information. Wave IV information about sexual orientation identity was used. Analyses were conducted within men and within women. We found modest support for the FBO effect in men, but not in women, using the older brother odds ratio, logistic regression analyses, and sibling sex ratio, which provided the strongest support for FBO. We found that gynephilic/biphilic women, but not androphilic/biphilic men, were more likely to be only-children compared to androphilic women and gynephilic men, respectively. We discuss limitations of the Add Health data and purported mechanisms for the FBO effect in men and the only-child effect in women.
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Affiliation(s)
- Malvina N Skorska
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, ON, L5L 1C6, Canada.
- Department of Psychology, Brock University, St. Catharines, ON, Canada.
| | - Anthony F Bogaert
- Department of Psychology, Brock University, St. Catharines, ON, Canada
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
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23
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Wang Y, Wu H, Sun ZS. The biological basis of sexual orientation: How hormonal, genetic, and environmental factors influence to whom we are sexually attracted. Front Neuroendocrinol 2019; 55:100798. [PMID: 31593707 DOI: 10.1016/j.yfrne.2019.100798] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/29/2019] [Accepted: 10/03/2019] [Indexed: 12/11/2022]
Abstract
Humans develop relatively stable attractions to sexual partners during maturation and present a spectrum of sexual orientation from homosexuality to heterosexuality encompassing varying degrees of bisexuality, with some individuals also displaying asexuality. Sexual orientation represents a basic life phenomenon for humans. However, the molecular mechanisms underlying these diverse traits of sexual orientation remain highly controversial. In this review, we systematically discuss recent advancements in sexual orientation research, including those related to measurements and associated brain regions. Current findings regarding sexual orientation modulation by hormonal, genetic, maternal immune system, and environmental factors are summarized in both human and model systems. We also emphasize that future studies should recognize the differences between males and females and pay more attention to minor traits and the epigenetic regulation of sexual orientation. A comprehensive view of sexual orientation may promote our understanding of the biological basis of sex, and that of human reproduction, and evolution.
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Affiliation(s)
- Yan Wang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Haoda Wu
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of the Chinese Academy of Sciences, Beijing 100190, China
| | - Zhong Sheng Sun
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of the Chinese Academy of Sciences, Beijing 100190, China; Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou 325000, China.
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24
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Nila S, Crochet PA, Barthes J, Rianti P, Juliandi B, Suryobroto B, Raymond M. Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia. EVOLUTIONARY PSYCHOLOGY 2019; 17:1474704919880701. [PMID: 31742436 PMCID: PMC10358421 DOI: 10.1177/1474704919880701] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/13/2019] [Indexed: 09/09/2023] Open
Abstract
Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal birth order (FBO) effect are universal features of MHP or not, we collected original data from homosexual men, heterosexual men, and heterosexual women from Java (Indonesia). Facial photographs were used to test whether homosexual faces are feminized when compared with heterosexual ones. We found that faces manipulated to resemble the average face of homosexual men are perceived as facially feminized, suggesting that homosexual men are facially feminized compared to heterosexual men, although a higher facial femininity was not captured by morphological analyses. Then, family data were used to detect differences in siblings' composition between homosexuals and heterosexuals. Homosexual men displayed a higher number of older brothers than heterosexual men, even when sibship size was controlled for, suggesting that the FBO effect exists in Indonesian populations. Independent of sexual orientation, men with older brothers seem more feminized than those without older brothers, consistent with the immune origin of the FBO effect. In conclusion, MHP in Indonesia is partially feminized and they have more older brothers. Such features are also associated with MHP in other cultural contexts, suggesting a cross-cultural effect of men homosexual preference. An evolutionary explanation is available for the feminizing effect, although the FBO effect remains unexplained even if proximal mechanisms start to be identified.
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Affiliation(s)
- Sarah Nila
- Department of Biology, Faculty of Mathematics and Natural Sciences, IPB University (Bogor Agricultural University), Indonesia
| | - Pierre-Andre Crochet
- CEFE, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, France
| | - Julien Barthes
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, France
| | - Puji Rianti
- Department of Biology, Faculty of Mathematics and Natural Sciences, IPB University (Bogor Agricultural University), Indonesia
| | - Berry Juliandi
- Department of Biology, Faculty of Mathematics and Natural Sciences, IPB University (Bogor Agricultural University), Indonesia
| | - Bambang Suryobroto
- Department of Biology, Faculty of Mathematics and Natural Sciences, IPB University (Bogor Agricultural University), Indonesia
| | - Michel Raymond
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, France
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25
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Swift-Gallant A, Coome LA, Aitken M, Monks DA, VanderLaan DP. Evidence for distinct biodevelopmental influences on male sexual orientation. Proc Natl Acad Sci U S A 2019; 116:12787-12792. [PMID: 31182568 PMCID: PMC6600923 DOI: 10.1073/pnas.1809920116] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Several biological mechanisms have been proposed to influence male sexual orientation, but the extent to which these mechanisms cooccur is unclear. Putative markers of biological processes are often used to evaluate the biological basis of male sexual orientation, including fraternal birth order, handedness, and familiality of same-sex sexual orientation; these biomarkers are proxies for immunological, endocrine, and genetic mechanisms. Here, we used latent profile analysis (LPA) to assess whether these biomarkers cluster within the same individuals or are present in different subgroups of nonheterosexual men. LPA defined four profiles of men based on these biomarkers: 1) A subgroup who did not have these biomarkers, 2) fraternal birth order, 3) handedness, and 4) familiality. While the majority of both heterosexual and nonheterosexual men were grouped in the profile that did not have any biomarker, the three profiles associated with a biomarker were composed primarily of nonheterosexual men. We then evaluated whether these subgroups differed on measures of gender nonconformity and personality that reliably show male sexual orientation differences. The subgroup without biomarkers was the most gender-conforming whereas the fraternal birth order subgroup was the most female-typical and agreeable, compared with the other profiles. Together, these findings suggest there are multiple distinct biodevelopmental pathways influencing same-sex sexual orientation in men.
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Affiliation(s)
- Ashlyn Swift-Gallant
- Department of Psychology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada;
| | - Lindsay A Coome
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Madison Aitken
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
- Child, Youth, and Emerging Adult Program, Centre for Addiction and Mental Health, Toronto, ON M6J 1H4, Canada
| | - D Ashley Monks
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada;
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON M6J 1H4, Canada
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26
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Wampold CH. The Association Between Fraternal Birth Order and Anal-Erotic Roles of Men Who Have Sex with Men. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:2445-2454. [PMID: 29956083 DOI: 10.1007/s10508-018-1237-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 03/06/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
The fraternal birth order effect (FBOE) describes the phenomenon that homosexual men tend to have a greater number of older brothers than do heterosexual men. The FBOE is a marker for an innate, biological predisposition for androphilia in genotypic males. The FBOE has been studied since the 1930s and is the most consistent biodemographic correlate of sexual orientation in men. This study sought to determine whether the FBOE applies equally to all men who have sex with men (MSM), or disproportionately to MSM whose anal intercourse behavior is predominantly receptive (Bottoms). Participants included 243 North American adult MSM who responded to advertisements posted on a Web site and other electronic media associated with the GALA festival, a quadrennial gathering of gay and lesbian choruses. Each was asked whether his anal intercourse behavior during the preceding year was predominantly receptive, predominantly penetrative, or about equally receptive and penetrative. Those who indicated their behavior was predominantly receptive were coded "Bottoms"; all others were coded "Not-Bottoms." Participants were also surveyed as to their sibship composition. Bottoms had a significantly greater mean number of older brothers than did Not-Bottoms. There was no significant difference with respect to older or younger sisters or younger brothers. Further, the older sibling sex ratio (OSSR) for the Bottom cohort, but not for the Not-Bottom cohort, was significantly higher than the expected OSSR for the general male population (OSSR = No. older brothers/No. older sisters × 100; expected OSSR for general population = 106). Thus, late fraternal birth order was correlated with receptive anal-erotic behavior among MSM.
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Affiliation(s)
- Charles H Wampold
- Collaborative Research Group on Health Policy and Promotion + UrbanHealth Lab, York College of the City University of New York, Jamaica, NY, USA.
- , 41 South Harrison Street, Princeton, NJ, 08540, USA.
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27
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Nila S, Barthes J, Crochet PA, Suryobroto B, Raymond M. Kin Selection and Male Homosexual Preference in Indonesia. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:2455-2465. [PMID: 29797146 DOI: 10.1007/s10508-018-1202-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 03/14/2018] [Accepted: 03/20/2018] [Indexed: 06/08/2023]
Abstract
Male homosexual preference (MHP) challenges evolutionary thinking because the preference for male-male relationships is heritable, implies a fertility cost (lower offspring number), and is relatively frequent in some societies (2-6% in Western countries) for a costly trait. It has been proposed that individuals with a MHP counterbalance reproductive costs through the transfer of resources to kin, thereby improving their indirect reproduction through kin's reproductive success. This kin selection hypothesis is not supported in Western countries and Japan, although consistent evidence has been obtained in Samoa. In this study, data from Java (Indonesia) were obtained to assess the avuncular tendencies of men with contrasting sexual orientation to measure possible resource transfer. Consistent with the kin selection hypothesis, males with a homosexual orientation reported an increased willingness to transfer resources toward nephews and nieces and declared having transferred more money to nephews and nieces. We developed a method to quantitatively estimate the contribution of kin selection on inclusive reproduction associated to sexual orientation, taking into account various possible biases. Kin selection reduced the direct reproductive cost of homosexual men by 20%, so suggesting that kin selection alone is insufficient to explain the maintenance of male homosexuality. Other potential factors are discussed, as well as the limitations of the study and the social determinant operating for the expression of increased avuncular tendencies of homosexual men.
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Affiliation(s)
- Sarah Nila
- Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Bogor, Indonesia
| | - Julien Barthes
- Institute of Evolutionary Sciences, CC065 Université de Montpellier, CNRS, IRD, EPHE, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
| | - Pierre-Andre Crochet
- CEFE, CNRS, Université de Montpellier - Université Paul-Valéry Montpellier-EPHE, Montpellier Cedex 05, France
| | - Bambang Suryobroto
- Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Bogor, Indonesia
| | - Michel Raymond
- Institute of Evolutionary Sciences, CC065 Université de Montpellier, CNRS, IRD, EPHE, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France.
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28
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Coome LA, Skorska MN, van der Miesen AI, Peragine DE, VanderLaan DP. An examination of the biodevelopment of gender expression in children ages 6- to 12-years. CANADIAN JOURNAL OF HUMAN SEXUALITY 2018. [DOI: 10.3138/cjhs.2018-0013] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Lindsay A. Coome
- Department of Psychology, University of Toronto, Mississauga, ON
| | | | - Anna I.R. van der Miesen
- Center of Expertise on Gender Dysphoria, VU University Medical Center, Amsterdam, The Netherlands
| | | | - Doug P. VanderLaan
- Department of Psychology, University of Toronto, Mississauga, ON
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON
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29
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O'Hanlan KA, Gordon JC, Sullivan MW. Biological origins of sexual orientation and gender identity: Impact on health. Gynecol Oncol 2018; 149:33-42. [PMID: 29605047 DOI: 10.1016/j.ygyno.2017.11.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 10/30/2017] [Accepted: 11/07/2017] [Indexed: 01/19/2023]
Abstract
Gynecologic Oncologists are sometimes consulted to care for patients who present with diverse gender identities or sexual orientations. Clinicians can create more helpful relationships with their patients if they understand the etiologies of these diverse expressions of sexual humanity. Multidisciplinary evidence reveals that a sexually dimorphic spectrum of somatic and neurologic anatomy, traits and abilities, including sexual orientation and gender identity, are conferred together during the first half of pregnancy due to genetics, epigenetics and the diversity of timing and function of sex chromosomes, sex-determining protein secretion, gonadal hormone secretion, receptor levels, adrenal function, maternally ingested dietary hormones, fetal health, and many other factors. Multiple layers of evidence confirm that sexual orientation and gender identity are as biological, innate and immutable as the other traits conferred during that critical time in gestation. Negative social responses to diverse orientations or gender identities have caused marginalization of these individuals with resultant alienation from medical care, reduced self-care and reduced access to medical care. The increased risks for many diseases, including gynecologic cancers are reviewed. Gynecologic Oncologists can potentially create more effective healthcare relationships with their patients if they have this information.
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Affiliation(s)
- Katherine A O'Hanlan
- Laparoscopic Institute for Gynecology and Oncology (LIGO), 4370 Alpine Rd. Suite 104, Portola Valley, CA 94028, United States.
| | - Jennifer C Gordon
- University of Tennessee Health Sciences Center, Memphis, TN, United States.
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Roselli CE. Neurobiology of gender identity and sexual orientation. J Neuroendocrinol 2018; 30:e12562. [PMID: 29211317 PMCID: PMC6677266 DOI: 10.1111/jne.12562] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/03/2017] [Accepted: 11/28/2017] [Indexed: 12/15/2022]
Abstract
Sexual identity and sexual orientation are independent components of a person's sexual identity. These dimensions are most often in harmony with each other and with an individual's genital sex, although not always. The present review discusses the relationship of sexual identity and sexual orientation to prenatal factors that act to shape the development of the brain and the expression of sexual behaviours in animals and humans. One major influence discussed relates to organisational effects that the early hormone environment exerts on both gender identity and sexual orientation. Evidence that gender identity and sexual orientation are masculinised by prenatal exposure to testosterone and feminised in it absence is drawn from basic research in animals, correlations of biometric indices of androgen exposure and studies of clinical conditions associated with disorders in sexual development. There are, however, important exceptions to this theory that have yet to be resolved. Family and twin studies indicate that genes play a role, although no specific candidate genes have been identified. Evidence that relates to the number of older brothers implicates maternal immune responses as a contributing factor for male sexual orientation. It remains speculative how these influences might relate to each other and interact with postnatal socialisation. Nonetheless, despite the many challenges to research in this area, existing empirical evidence makes it clear that there is a significant biological contribution to the development of an individual's sexual identity and sexual orientation.
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Affiliation(s)
- C E Roselli
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, USA
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Swift-Gallant A, Coome LA, Monks DA, VanderLaan DP. Gender Nonconformity and Birth Order in Relation to Anal Sex Role Among Gay Men. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:1041-1052. [PMID: 28378093 DOI: 10.1007/s10508-017-0980-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 03/18/2017] [Accepted: 03/20/2017] [Indexed: 06/07/2023]
Abstract
Androphilia is associated with an elevated number of older brothers among natal males. This association, termed the fraternal birth order effect, has been observed among gay men who exhibit marked gender nonconformity. Gender nonconformity has been linked to gay men's preferred anal sex role. The present study investigated whether these two lines of research intersect by addressing whether the fraternal birth order effect was associated with both gender nonconformity and a receptive anal sex role (243 gay men, 91 heterosexual men). Consistent with previous research, we identified the fraternal birth order effect in our sample of gay men. Also, gay men were significantly more gender-nonconforming on adulthood and recalled childhood measures compared to heterosexual men. When gay men were compared based on anal sex role (i.e., top, versatile, bottom), all groups showed significantly greater recalled childhood and adult male gender nonconformity than heterosexual men, but bottoms were most nonconforming. Only gay men with a bottom anal sex role showed evidence of a fraternal birth order effect. A sororal birth order effect was found in our sample of gay men, driven by versatiles. No significant associations were found between fraternal birth order and gender nonconformity measures. These results suggest that the fraternal birth order effect may apply to a subset of gay men who have a bottom anal sex role preference and that this subgroup is more gender-nonconforming. However, there were no significant associations between fraternal birth order and gender nonconformity at the individual level. As such, based on the present study, whether processes underpinning the fraternal birth order effect influence gender nonconformity is equivocal.
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Affiliation(s)
- Ashlyn Swift-Gallant
- Department of Psychology, University of Toronto, 100 St. George St., Toronto, ON, M5S 3G3, Canada
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada
| | - Lindsay A Coome
- Department of Psychology, University of Toronto, 100 St. George St., Toronto, ON, M5S 3G3, Canada
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada
| | - D Ashley Monks
- Department of Psychology, University of Toronto, 100 St. George St., Toronto, ON, M5S 3G3, Canada
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto, 100 St. George St., Toronto, ON, M5S 3G3, Canada.
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada.
- Underserved Populations Research Program, Child, Youth and Family Division, Centre for Addiction and Mental Health, 1001 Queen St. W., Toronto, ON, M6J 1H4, Canada.
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Gavrilets S, Friberg U, Rice WR. Understanding Homosexuality: Moving on from Patterns to Mechanisms. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:27-31. [PMID: 28986707 DOI: 10.1007/s10508-017-1092-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/26/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Sergey Gavrilets
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA.
- Department of Mathematics, University of Tennessee, Knoxville, TN, USA.
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, USA.
| | - Urban Friberg
- IFM Biology, Linkoping University, Linkoping, Sweden
| | - William R Rice
- Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA
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Early life conditions, reproductive and sexuality-related life history outcomes among human males: A systematic review and meta-analysis. EVOL HUM BEHAV 2018. [DOI: 10.1016/j.evolhumbehav.2017.08.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Swift-Gallant A, Breedlove SM. O Gay New World: Ramifications of the Maternal Immune Hypothesis. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:39-41. [PMID: 29188406 DOI: 10.1007/s10508-017-1118-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 11/13/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Ashlyn Swift-Gallant
- Neuroscience Program and Departments of Psychology and Integrative Biology, Michigan State University, 293 Farm Lane, East Lansing, MI, 48824, USA
| | - S Marc Breedlove
- Neuroscience Program and Departments of Psychology and Integrative Biology, Michigan State University, 293 Farm Lane, East Lansing, MI, 48824, USA.
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Fraternal birth order effect on sexual orientation explained. Proc Natl Acad Sci U S A 2017; 115:234-236. [PMID: 29259109 DOI: 10.1073/pnas.1719534115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Gay men have, on average, a greater number of older brothers than do heterosexual men, a well-known finding within sexual science. This finding has been termed the fraternal birth order effect. Strong scientific interest in sexual orientation exists because it is a fundamental human characteristic, and because its origins are often the focal point of considerable social controversy. Our study is a major advance in understanding the origins of sexual orientation in men by providing support for a theorized but previously unexamined biological mechanism—a maternal immune response to a protein important in male fetal brain development—and by beginning to explain one of the most reliable correlates of male homosexuality: older brothers. We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development—protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)—were developed. Plasma from mothers of sons, about half of whom had a gay son, along with additional controls (women with no sons, men) was analyzed for male protein-specific antibodies. Results indicated women had significantly higher anti-NLGN4Y levels than men. In addition, after statistically controlling for number of pregnancies, mothers of gay sons, particularly those with older brothers, had significantly higher anti-NLGN4Y levels than did the control samples of women, including mothers of heterosexual sons. The results suggest an association between a maternal immune response to NLGN4Y and subsequent sexual orientation in male offspring.
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Hughes SK, VanderLaan DP, Blanchard R, Wood H, Wasserman L, Zucker KJ. The Prevalence of Only-Child Status Among Children and Adolescents Referred to a Gender Identity Service Versus a Clinical Comparison Group. JOURNAL OF SEX & MARITAL THERAPY 2017; 43:586-593. [PMID: 27399602 DOI: 10.1080/0092623x.2016.1208702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Several studies indicate that homosexual males have a high proportion of older brothers compared to heterosexual males. Natal males with gender dysphoria who are likely to be homosexual also display this sibship pattern. Until recently, there was little evidence linking homosexuality and/or gender dysphoria in females to unique sibship characteristics. Two studies have indicated that natal female youth clinically referred for gender dysphoria are more likely to be only children (Schagen, Delemarre-van de Waal, Blanchard, & Cohen-Kettenis, 2012; VanderLaan, Blanchard, Wood, & Zucker, 2014). However, these studies did not include control groups of youth clinically referred for other reasons. Thus, it is unclear whether the increased likelihood of only-child status is specific to gender-referred natal females. This study compared only-child status among youth referred to a mental health service for gender dysphoria (778 males, 245 females) versus other reasons (783 males, 281 females). Prehomosexual gender-referred males were less likely to be only children than clinical controls. Contrary to previous findings, gender-referred females were not more likely to be only children, indicating that increased likelihood of only-child status is not specific to gender-referred females, but is characteristic of clinic-referred females more generally.
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Affiliation(s)
- S Kathleen Hughes
- a Underserved Populations Research Program, Child, Youth and Family Division , Centre for Addiction and Mental Health , Toronto , Ontario , Canada
| | - Doug P VanderLaan
- a Underserved Populations Research Program, Child, Youth and Family Division , Centre for Addiction and Mental Health , Toronto , Ontario , Canada
- b Department of Psychology , University of Toronto Mississauga , Mississauga , Ontario , Canada
| | - Ray Blanchard
- c Department of Psychiatry , University of Toronto , Toronto , Ontario , Canada
| | - Hayley Wood
- a Underserved Populations Research Program, Child, Youth and Family Division , Centre for Addiction and Mental Health , Toronto , Ontario , Canada
| | - Lori Wasserman
- a Underserved Populations Research Program, Child, Youth and Family Division , Centre for Addiction and Mental Health , Toronto , Ontario , Canada
| | - Kenneth J Zucker
- c Department of Psychiatry , University of Toronto , Toronto , Ontario , Canada
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Skorska MN, Bogaert AF. Prenatal Androgens in Men's Sexual Orientation: Evidence for a More Nuanced Role? ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:1621-1624. [PMID: 28534216 DOI: 10.1007/s10508-017-1000-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/06/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Malvina N Skorska
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
| | - Anthony F Bogaert
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
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Liu L, Cheng J, Li H, Su Y, Sun L, Yang L, Qian Q, Wang Y. Association of Y-linked variants with impulsivity and aggression in boys with attention-deficit/hyperactivity disorder of Chinese Han descent. Psychiatry Res 2017; 252:185-187. [PMID: 28284086 DOI: 10.1016/j.psychres.2017.02.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 10/20/2022]
Abstract
Y chromosome plays important role in brain function and may help to explain the sex difference in attention-deficit/hyperactivity disorder (ADHD). A total of 857 boys with ADHD and 574 male controls were genotyped for 14 Y-linked markers. Analyses for both dichotomous phenotype and quantitative traits and the interaction effects with MAOA were performed. The results indicated significant association of four markers (M88, M95, M175, and M119) with inhibition function and aggression in boys with ADHD. Positive interaction effects with MAOA were also detected. In conclusion, some Y-linked variants may be associated with the impulsivity and aggression in boys with ADHD.
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Affiliation(s)
- Lu Liu
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Jia Cheng
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Haimei Li
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Yi Su
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Li Sun
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Li Yang
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China
| | - Qiujin Qian
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China.
| | - Yufeng Wang
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China; National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, China.
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40
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Brotto LA, Yule MA. Response to Commentaries. ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:653-657. [PMID: 28332038 DOI: 10.1007/s10508-017-0974-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 03/09/2017] [Indexed: 06/06/2023]
Affiliation(s)
- Lori A Brotto
- Department of Obstetrics and Gynaecology, University of British Columbia, 2775 Laurel Street, 6th Floor, Vancouver, BC, V5Z 1M9, Canada.
| | - Morag A Yule
- Department of Obstetrics and Gynaecology, University of British Columbia, 2775 Laurel Street, 6th Floor, Vancouver, BC, V5Z 1M9, Canada
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41
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Bogaert AF. What Asexuality Tells Us About Sexuality. ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:629-630. [PMID: 27832370 DOI: 10.1007/s10508-016-0892-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 10/24/2016] [Indexed: 06/06/2023]
Affiliation(s)
- Anthony F Bogaert
- Department of Health Sciences and Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
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42
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Semenyna SW, VanderLaan DP, Vasey PL. Birth order and recalled childhood gender nonconformity in Samoan men and fa'afafine. Dev Psychobiol 2017; 59:338-347. [PMID: 28261795 DOI: 10.1002/dev.21498] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 12/10/2016] [Indexed: 11/12/2022]
Abstract
Having a greater than average number of older biological brothers is a robust correlate of male androphilia (i.e., sexual attraction and arousal to adult males). Previous investigations have sought to understand whether this fraternal birth order (FBO) effect is also systematically related to recalled indicators of childhood gender nonconformity (CGN). However, these investigations have relied on data from low-fertility Western populations in which expressions of femininity in male children are routinely stigmatized and consequently, suppressed. The present study examined the FBO effect (among other sibship characteristics) and recalled indicators of CGN in Samoa, a high-fertility population, whose members are relatively tolerant of male femininity. Indeed, Samoans identify feminine androphilic males as belonging to an alternative gender category, known locally as fa'afafine. The present study compared the sibship characteristics of 231 fa'afafine and 231 opposite-sex attracted men from Samoa, as well as how these characteristics related to recalled CGN. Results replicated the well-established FBO effect for predicting male sexual orientation, with each older brother increasing the odds of being androphilic by 21%. However, no relationship was found between the number of older brothers (or other siblings) a participant had and their recalled CGN. Although fa'afafine reported significantly more CGN than Samoan men, CGN did not mediate the FBO effect, nor did the FBO effect and CGN interact to predict male sexual orientation. These findings are consistent with previous studies suggesting that the FBO effect is associated with male sexual orientation, but not childhood female-typical gender expression among androphilic males.
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Affiliation(s)
- Scott W Semenyna
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, Toronto, Ontario, Canada.,Underserved Populations Research Program, Child, Youth, and Family Division, Center for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada
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Prenatal administration of letrozole reduces SDN and SCN volume and cell number independent of partner preference in the male rat. Physiol Behav 2017; 171:61-68. [PMID: 28057567 DOI: 10.1016/j.physbeh.2017.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 12/30/2016] [Accepted: 01/01/2017] [Indexed: 12/17/2022]
Abstract
During development, the exposure to testosterone, and its conversion to estradiol by an enzyme complex termed aromatase, appears to be essential in adult male rats for the expression of typical male sexual behavior and female-sex preference. Some hypothalamic areas are the supposed neural bases of sexual preference/orientation; for example, male-oriented rams have a reduced volume of the sexually dimorphic nucleus (oSDN), while in homosexual men this nucleus does not differ from that of heterosexual men. In contrast, homosexual men showed a larger number of vasopressinergic cells in the suprachiasmatic nucleus (SCN). Interestingly, male rats perinatally treated with an aromatase inhibitor, 1,4,6-androstatriene-3,17-dione (ATD), also showed bisexual preference and an increased number of vasopressinergic neurons in the SCN. However, this steroidal aromatase inhibitor has affinity for all three steroid receptors. Recently, we reported that the prenatal administration of the selective aromatase inhibitor, letrozole, produced a subpopulation of males with same-sex preference. The aim of this study was to compare the volume and number of cells of the SDN and SCN (the latter nucleus was immunohistochemically stained for vasopressin) between males treated with letrozole with same-sex preference, males treated with letrozole with female preference and control males with female preference. Results showed that all males prenatally treated with letrozole have a reduced volume and estimated cell number in the SDN and SCN, independent of their partner preference. These results indicate that the changes in these brain areas are not related to sexual preference, but rather to the effects of letrozole. The divergent results may be explained by species differences as well as by the critical windows during which the aromatase inhibitor was administered.
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Skorska MN, Bogaert AF. Pubertal Stress and Nutrition and their Association with Sexual Orientation and Height in the Add Health Data. ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:217-236. [PMID: 27511207 PMCID: PMC5925759 DOI: 10.1007/s10508-016-0800-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 06/03/2016] [Accepted: 06/22/2016] [Indexed: 05/29/2023]
Abstract
A number of studies have indicated that gay men tend to be shorter, on average, than heterosexual men. Less evidence exists that lesbian women are taller, on average, than heterosexual women. The most popular explanation of the association between sexual orientation and height involves prenatal factors, such that, for example, gay men may have been exposed to lower than typical androgens during fetal development, which impacts their height and sexual orientation as adults. An alternative explanation involves stress, given that stress has been associated with sexual minority identification and with lower height. Another alternative explanation involves nutrition, although its relationship is less clear with sexual minority identification. Using the Add Health data, which is a large, nationally representative and longitudinal sample of American adolescents (n = 14,786), we tested a mediation model, such that sexual orientation → pubertal stress/nutrition → height. Within men, we found that gay men (n = 126) were shorter, on average, than heterosexual men (n = 6412). None of the 24 pubertal stress-related and 15 pubertal nutrition-related variables assessed in the Add Health data mediated the relationship between sexual orientation and height in men. Within women, lesbians (n = 75) did not differ significantly in stature compared to heterosexual women (n = 6267). Thus, prenatal mechanisms (e.g., hormones, maternal immune response) are likely better candidates for explaining the height difference between gay men and heterosexual men.
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Affiliation(s)
- Malvina N Skorska
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
| | - Anthony F Bogaert
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
- Department of Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
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45
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Skorska MN, Blanchard R, VanderLaan DP, Zucker KJ, Bogaert AF. Gay Male Only-Children: Evidence for Low Birth Weight and High Maternal Miscarriage Rates. ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:205-215. [PMID: 27549305 DOI: 10.1007/s10508-016-0829-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 05/24/2016] [Accepted: 08/02/2016] [Indexed: 06/06/2023]
Abstract
Recent findings suggest that there may be a maternal immune response underpinning the etiology of sexual orientation of gay male only-children. This maternal immune response appears to be distinct from that which is purported to explain the classic fraternal birth order effect found in studies of male sexual orientation. We tested two predictions related to the hypothesized maternal immune response in mothers of gay male only-children: (1) elevated fetal loss among mothers who have had gay male only-children and (2) lower birth weight in gay male only-children. Mothers of at least one gay son (n = 54) and mothers of heterosexual son(s) (n = 72) self-reported their pregnancy histories, including the birth weights of newborns and number of fetal losses (e.g., miscarriages). Mothers of gay male only-children (n = 8) reported significantly greater fetal loss compared with mothers of males with four other sibship compositions (gay with no older brothers, gay with older brothers, heterosexual only-children, heterosexual with siblings) (n = 118). Also, firstborn gay male only-children (n = 4) had a significantly lower birth weight than firstborn children in the four other sibship compositions (n = 59). Duration of pregnancy was not significantly different among the groups of firstborn children in the birth weight analyses. Thus, this study found further support for a distinct pattern of maternal immune response implicated in the etiology of male sexual orientation. Mechanisms that may underlie this potential second type of maternal immune response are discussed.
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Affiliation(s)
- Malvina N Skorska
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
| | - Ray Blanchard
- Department of Psychiatry, University of Toronto, 250 College Street, Toronto, ON, M5T 1R8, Canada
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road N., Mississauga, ON, L5L 1C6, Canada
- Child, Youth and Family Division, Underserved Populations Research Program, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Kenneth J Zucker
- Department of Psychiatry, University of Toronto, 250 College Street, Toronto, ON, M5T 1R8, Canada
| | - Anthony F Bogaert
- Department of Psychology, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
- Department of Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
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46
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Skorska MN, Bogaert AF. Sexual Orientation, Objective Height, and Self-Reported Height. JOURNAL OF SEX RESEARCH 2017; 54:19-32. [PMID: 26813611 DOI: 10.1080/00224499.2015.1124831] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Studies that have used mostly self-reported height have found that androphilic men and women are shorter than gynephilic men and women, respectively. This study examined whether an objective height difference exists or whether a psychosocial account (e.g., distortion of self-reports) may explain these putative height differences. A total of 863 participants, recruited at a Canadian university, the surrounding region, and through lesbian, gay, bisexual, and transgender (LGBT) events across Canada, self-reported their height and had their height measured. Androphilic men were shorter, on average, than gynephilic men. There was no objective height difference between gynephilic, ambiphilic, and androphilic women. Self-reported height, statistically controlling for objective height, was not related to sexual orientation. These findings are the first to show an objective height difference between androphilic and gynephilic men. Also, the findings suggest that previous studies using self-reported height found part of a true objective height difference between androphilic and gynephilic men. These findings have implications for existing biological theories of men's sexual orientation development.
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Affiliation(s)
| | - Anthony F Bogaert
- b Department of Psychology and Department of Health Sciences , Brock University
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Hames R, Garfield Z, Garfield M. Is Male Androphilia a Context-Dependent Cross-Cultural Universal? ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:63-71. [PMID: 28028666 DOI: 10.1007/s10508-016-0855-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 08/06/2016] [Accepted: 09/02/2016] [Indexed: 06/06/2023]
Abstract
The cross-cultural ethnographic literature has traditionally used the label male "homosexuality" to describe sexual relationships between biological males without considering whether or not the concept encompasses primary sexual attraction to adult males. Although male androphilia seems to be found in all national populations, its universal existence in tribal populations has been questioned. Our goal is to review previous cross-cultural classifications and surveys of male same sex behavior to present a system that does justice to its varied expressions, especially as it is informed by contemporary sexuality research. Previous comparative research does not effectively distinguish male same sex behavior from male androphilia. Using the standard cross-cultural sample (SCCS) as a sampling frame and the ethnographic sources in the human relations area files and elsewhere, we present distributional data on various forms of male same sex behavior. The SCCS is useful because it is designed to be representative of all historically known social formations and the sample is designed to reduce similarities as a consequence of common descent or historical origin as well as reduce the probability of diffusion of sociocultural practices from one culture to another. Our results show that male same sex behavior as well as male androphilia is much more common than previously estimated in the SCCS. With our findings, we make an argument that male androphilia is a context-dependent cross-cultural universal.
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Affiliation(s)
- Raymond Hames
- Department of Anthropology, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
| | - Zachary Garfield
- Department of Anthropology, University of Washington-Vancouver, Vancouver, WA, 98686, USA
| | - Melissa Garfield
- Department of Anthropology, University of Washington-Vancouver, Vancouver, WA, 98686, USA
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Gómez FR, Semenyna SW, Court L, Vasey PL. Recalled Separation Anxiety in Childhood in Istmo Zapotec Men, Women, and Muxes. ARCHIVES OF SEXUAL BEHAVIOR 2017; 46:109-117. [PMID: 28050743 DOI: 10.1007/s10508-016-0917-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/29/2016] [Accepted: 12/07/2016] [Indexed: 06/06/2023]
Abstract
The Istmo Zapotec are a pre-Columbian cultural group indigenous to the Istmo region of Oaxaca, Mexico. Istmo Zapotec recognize three genders: men, women, and muxes. Like Istmo Zapotec men, muxes are biological males. However, unlike Istmo Zapotec men, most muxes are exclusively androphilic (i.e., sexually attracted to adult males), relatively feminine, and routinely adopt the receptive role during anal intercourse. Furthermore, the Istmo Zapotec recognize two types of muxes: muxe gunaa, who resemble the transgender androphilic males that are common in many non-Western cultures, and muxe nguiiu, who resemble the cisgender androphilic males ("gay" men) common in Western cultures. Retrospective research conducted in Canada and Samoa demonstrates that cisgender and transgender androphilic males recall elevated indicators of childhood separation anxiety (i.e., feelings of distress related to separation from major attachment figures) when compared to males who are gynephilic (i.e., sexually attracted to adult females). The present study compared recalled indicators of childhood separation anxiety among Istmo Zapotec men, women, muxe gunaa, and muxe nguiiu (N = 454). Men recalled significantly lower levels of childhood separation anxiety compared to all other groups (all p < .042). No additional group differences were found. Our results are consistent with previous research conducted in Canada and Samoa, suggesting that elevated childhood separation anxiety is a developmental correlate of male androphilia that is cross-culturally universal. This research is also consistent with the conclusion that cisgender and transgender male androphiles share a common biological and developmental foundation despite being different in appearance.
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Affiliation(s)
- Francisco R Gómez
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada.
| | - Scott W Semenyna
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
| | - Lucas Court
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
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Maitra A, Maitra C, Jha DK, Biswas R. Finger Length Ratio (2D:4D) in Central India and an Attempt to Verify Fraternal Birth Order Effect: A Population Based Cross-Sectional Study. J Clin Diagn Res 2016; 10:CC09-CC12. [PMID: 28208849 PMCID: PMC5296422 DOI: 10.7860/jcdr/2016/21978.9001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/22/2016] [Indexed: 11/24/2022]
Abstract
INTRODUCTION A normal physiology of a human being is not mere a series of functions occurring with specific intensities and timing. There are lot of factors that may change the normal physiological activity within normal limits. Finger length ratio is one of the markers of intrauterine androgen exposure and it is debated and contradicted by many authors. Digit ratio varies among the ethnicities. Many Indian studies show that there is considerable difference in finger length ratio in different population. Data regarding Central India was not found on extensive search. AIM To find out the finger length ratio and explore the birth order effect on finger length ratio among the first two successive born in the said population. MATERIALS AND METHODS We conducted a survey on 1500 volunteer persons (800 male and 700 female) over two years of time. We measured the length of the index finger (2D) and ring finger (4D) of both the hands and asked about their birth order history to find out the digit ratio for Central India population and any existing correlation of the same with birth order. T Test and Analysis of Variance (ANOVA) were used for the measure of significance and difference among the groups. The p< 0.05 was considered to be significant. RESULTS Our study reports that, study population mean for right hand 2D:4D ratio was 0.976 (SD±0.031) and for left hand it was found to be 0.969 (SD±0.035). For males, mean finger length ratio for right hand was 0.967 (SD±0.033) and 0.963 (SD±0.037) for left hand. In females the mean Finger length ratio was 0.982 (SD±0.027) for right hand and 0.974 (SD±0.034) for the left hand respectively. Finger length ratio was found to be significantly less (p=0.03) in males for right hand. No significant (p=0.24) difference was observed for left hand. When assessed fraternal birth order effect among the eldest, second born with elder brother and second born with elder sister groups, no significant (p>0.05) variation for finger length ratio of right and left hands observed in both male and female population. CONCLUSION Our study reports that the finger length ratio (2D:4D) for Central India population did not show significant association between finger length ratio and fraternal birth order among the first two successive born.
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Affiliation(s)
- Arjun Maitra
- Assistant Professor, Department of Physiology, Modern Institute of Medical Sciences, Kanadia Indore, Madhya Pradesh, India
| | - Chaitali Maitra
- Assistant Professor, Department of Biochemistry, Modern Institute of Medical Sciences, Kanadia Indore, Madhya Pradesh, India
| | - Dilip Kumar Jha
- Professor and Head of Department, Department of Physiology, Sikkim Manipal Institute of Medical Sciences, Tadong Gangtok, Sikkim, Assam, India
| | - Rakesh Biswas
- Professor, Department of Medicine, L.N. Medical College and Research Centre, Bhopal, Madhya Pradesh, India
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Kramer P, Bressan P. Humans as Superorganisms: How Microbes, Viruses, Imprinted Genes, and Other Selfish Entities Shape Our Behavior. PERSPECTIVES ON PSYCHOLOGICAL SCIENCE 2016; 10:464-81. [PMID: 26177948 DOI: 10.1177/1745691615583131] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Psychologists and psychiatrists tend to be little aware that (a) microbes in our brains and guts are capable of altering our behavior; (b) viral DNA that was incorporated into our DNA millions of years ago is implicated in mental disorders; (c) many of us carry the cells of another human in our brains; and (d) under the regulation of viruslike elements, the paternally inherited and maternally inherited copies of some genes compete for domination in the offspring, on whom they have opposite physical and behavioral effects. This article provides a broad overview, aimed at a wide readership, of the consequences of our coexistence with these selfish entities. The overarching message is that we are not unitary individuals but superorganisms, built out of both human and nonhuman elements; it is their interaction that determines who we are.
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Affiliation(s)
- Peter Kramer
- Department of General Psychology, University of Padua, Italy
| | - Paola Bressan
- Department of General Psychology, University of Padua, Italy
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