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Pickstone-Taylor SD, Davids EL, de Bever GN, de Vries PJ. Demographic and mental health profile of youth in a gender service: An African case series. S Afr J Psychiatr 2024; 30:2160. [PMID: 38726329 PMCID: PMC11079370 DOI: 10.4102/sajpsychiatry.v30i0.2160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 02/07/2024] [Indexed: 05/12/2024] Open
Abstract
Background Despite a massive global increase in research on gender-diverse youth, there have been no studies in Africa on gender-diverse children and adolescents presenting to health services. Aim This study aimed to present the first African findings of the demographic and mental health profile of youth who have presented at a gender service in South Africa. Setting A specialist mental health outpatient service, consisting of psychiatry, psychology and nursing input, for gender-diverse child and adolescent patients in the Western Cape. Methods All consenting youth seen at a gender service, consisting of psychiatry, psychology and nursing input, in state and by the same clinician in private practice between January 2012 and May 2019 were participants of a retrospective, sequential case series study. Data of interest, including gender identity and sexuality, mental health history and social information, were extracted from the psychiatry files of participants. Results Thirty-nine participants were part of the registry and qualified for the study: 72% self-identified as white, 15% as coloured and 13% as black African. The rate of co-occurring psychopathology was high (64%) and included high rates of autism, particularly in trans males (26%), suicidal ideation in 31% and a history of suicide attempt(s) in 10%. Conclusions This first study describing gender-diverse youth seeking support relating to their gender identity in Africa showed they had remarkable similarities to those studied internationally. Contribution Establishing that transgender youth of all major racial groups in the province with similar demographic profiles to other parts of the world are presenting to services in South Africa and in need of mental health support and interventions.
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Affiliation(s)
- Simon D Pickstone-Taylor
- Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Eugene L Davids
- Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Graham N de Bever
- Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Petrus J de Vries
- Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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2
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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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3
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Baams L, Kaufman TML. Sexual Orientation and Gender Identity/Expression in Adolescent Research: Two Decades in Review. JOURNAL OF SEX RESEARCH 2023; 60:1004-1019. [PMID: 37307300 DOI: 10.1080/00224499.2023.2219245] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
There is a long history of research among adolescents who are minoritized and marginalized for their sexual orientation and gender identity/expression (SOGIE). However, it remains unclear how we can best conceptualize and assess SOGIE in adolescence, resulting in different subpopulations and findings across studies. Addressing this issue, we present a narrative literature review of the conceptualization and assessment of SOGIE, and provide recommendations for conceptualizing and operationalizing these concepts. Our review indicated that most research with adolescent populations still almost exclusively assesses isolated dimensions of sexuality and gender (e.g., attraction but not identity). We argue that to make research inclusive and equitable, scholars are required to make clear substantiated decisions and be transparent about the SOGIE dimensions and, thus, subpopulations they represent.
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Affiliation(s)
- Laura Baams
- Department of Pedagogy and Educational Sciences, University of Groningen
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4
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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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5
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Blanchard R, Skorska MN. New Data on Birth Order in Homosexual Men and Women and a Reply to Vilsmeier et al. (2021a, 2021b). ARCHIVES OF SEXUAL BEHAVIOR 2022; 51:3319-3349. [PMID: 35713755 DOI: 10.1007/s10508-022-02362-z] [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: 01/18/2022] [Revised: 05/28/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
The fraternal birth order effect (FBOE) is the repeated finding that older brothers increase the odds of homosexuality in later-born males. It has been our working assumption, based on the majority of previous studies, that a similar FBOE does not occur in females. In an elaborate quantitative review posted last year to a preprint server, Vilsmeier et al. (2021a) concluded that there is no valid evidence for an FBOE in men or women. Ablaza et al. (2022) subsequently published a study of population-level data from the Netherlands with conclusions completely opposite to those of Vilsmeier et al., namely, that there is robust evidence of an FBOE in both men and women. The present research was initially undertaken to refute the assertion of Vilsmeier et al. that there is no proof of an FBOE in men and to investigate how they obtained such a discrepant conclusion. We found evidence that the discrepancy may relate to Vilsmeier et al.'s use of the large and demonstrably unreliable sample published by Frisch and Hviid (2006). After the publication by Ablaza et al., we expanded our article to address their finding of an FBOE in women. We argue that our preferred explanation of the FBOE in men-that it reflects the progressive immunization of some mothers to Y-linked antigen by each succeeding male fetus and the concomitantly increasing effects of anti-male antibody on sexual differentiation in the brain in each succeeding male fetus-could plausibly be extended to female homosexuality.
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Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada.
| | - Malvina N Skorska
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada
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6
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Li L, Duan X, Wang H, Sun Y, Zhao W, Lu Y, Xu H, You Y, Wang Q. Is cell regeneration and infiltration a double edged sword for porcine aortic valve deterioration? A large cohort of histopathological analysis. BMC Cardiovasc Disord 2022; 22:336. [PMID: 35902792 PMCID: PMC9335994 DOI: 10.1186/s12872-022-02776-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 07/12/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Bioprostheses are the most common prostheses used for valve replacement in the Western medicine. The major flaw of bioprostheses is the occurrence of structural valve deterioration (SVD). This study aimed to assess the pathological features of porcine aortic valve (PAV)-SVD based on histomorphological and immunopathological characteristics of a large cohort of patients. METHODS Histopathological data of 109 cases with resected PAV were collected. The type and amount of infiltrated cells were evaluated in the different types of bioprosthetic SVD by immunohistochemical staining. RESULTS The most common cause of SVD was calcification, leaflet tear, and dehiscence (23.9%, 19.3%, and 18.3%, respectively). Immunohistochemical staining demonstrated that macrophages were infiltrated in the calcified, lacerated and dehiscence PAV, in which both M1 and M2 macrophages were existed in the calcified PAV. Importantly, the higher content of M1 macrophages and less content of M2 macrophages were found in the lacerated and dehiscence PAV, and MMP-1 expression was mainly found in the lacerated PAV. The endothelialization rate of leaflet dehiscence was higher than that of calcified and lacerated leaflets. A large number of CD31+/CD11b+ cells was aggregated in the spongy layer in the lacerated and dehiscence PAV. CONCLUSION Cell regeneration and infiltration is a double edged sword for the PAV deterioration. Macrophage infiltration is involved in the different types of SVD, while only MMP-1 expression is involved in lacerated leaflets. The macrophage subtype of circulating angiogenic cells in dehiscence and tear PAV could be identified, which could reserve macrophages in the PAV-SVD.
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Affiliation(s)
- Li Li
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China.
| | - Xuejing Duan
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Hongyue Wang
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Yang Sun
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Wei Zhao
- Center for Adult Surgery, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Yang Lu
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Hongyu Xu
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Yiwei You
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
| | - Qingzhi Wang
- Department of Pathology, Fuwai Hospital, Peking UnionMedical College, Chinese Academy of Medical Science, Beilishi Road No. 167, Xicheng District, Beijing, 100037, China
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7
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Blanchard R, Beier KM, Gómez Jiménez FR, Grundmann D, Krupp J, Semenyna SW, Vasey PL. Meta-Analyses of Fraternal and Sororal Birth Order Effects in Homosexual Pedophiles, Hebephiles, and Teleiophiles. ARCHIVES OF SEXUAL BEHAVIOR 2021; 50:779-796. [PMID: 32895872 DOI: 10.1007/s10508-020-01819-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/19/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
This study investigated the relations between numbers of older brothers, numbers of older sisters, and the odds of homosexuality in later-born males, including males who are most attracted sexually to prepubescent or early pubescent children (pedohebephiles) and males who are most attracted sexually to adults (teleiophiles). The authors meta-analyzed data from 24 samples of homosexual and heterosexual men, originally reported in 18 studies, and totaling 18,213 subjects. The results confirmed that older brothers increase the odds of same-sex preference in pedohebephiles as they do in teleiophiles. They also replicated the recent finding that older sisters have a similar but weaker statistical association with the odds of homosexuality. These findings have two theoretical implications. First, the findings for older brothers and older sisters indicate some commonality in the factors that influence sexual preference in teleiophiles and those that influence sexual preference in pedohebephiles. Second, the finding for older sisters confirms a prediction stemming from the hypothesis that male fetuses stimulate maternal antibodies that increase the odds of homosexuality in later-born males. Such immunization could result from miscarried as well as full-term fetuses, and number of older sisters should correlate with number of male fetuses miscarried before gestation of the subject.
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Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada.
| | - Klaus M Beier
- Department of Health and Human Sciences, Institute of Sexology and Sexual Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Dorit Grundmann
- Department of Health and Human Sciences, Institute of Sexology and Sexual Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jurian Krupp
- Department of Health and Human Sciences, Institute of Sexology and Sexual Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Scott W Semenyna
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
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8
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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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9
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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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10
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Birth Order and Sibling Sex Ratio in Androphilic Males and Gynephilic Females Diagnosed With Gender Dysphoria From Iran. J Sex Med 2020; 17:1195-1202. [DOI: 10.1016/j.jsxm.2020.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/17/2020] [Accepted: 02/02/2020] [Indexed: 12/22/2022]
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11
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Blanchard R, Krupp J, VanderLaan DP, Vasey PL, Zucker KJ. A method yielding comparable estimates of the fraternal birth order and female fecundity effects in male homosexuality. Proc Biol Sci 2020; 287:20192907. [PMID: 32183625 PMCID: PMC7126035 DOI: 10.1098/rspb.2019.2907] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/26/2020] [Indexed: 12/16/2022] Open
Abstract
The fraternal birth order effect (FBOE) is the finding that older brothers increase the probability of homosexuality in later-born males, and the female fecundity effect (FFE) is the finding that the mothers of homosexual males produce more offspring than the mothers of heterosexual males. In a recent paper, Khovanova proposed a novel method for computing independent estimates of these effects on the same samples and expressing the magnitude and direction of the effects in the same metric. In her procedure, only families with one or two sons are examined, and daughters are ignored. The present study investigated the performance of Khovanova's method using archived data from 10 studies, comprising 14 samples totalling 5390 homosexual and heterosexual subjects. The effect estimate for the FBOE showed that an increase from zero older brothers to one older brother is associated with a 38% increase in the odds of homosexuality. By contrast, the effect estimate for the FFE showed that the increase from zero younger brothers to one younger brother is not associated with any increase in the odds of homosexuality. The former result supports the maternal immune hypothesis of male homosexuality; the latter result does not support the balancing selection hypothesis.
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Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Jurian Krupp
- Department of Health and Human Sciences, Institute of Sexology and Sexual Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Doug P. VanderLaan
- Department of Psychology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Paul L. Vasey
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Kenneth J. Zucker
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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12
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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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13
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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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14
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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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Blanchard R. Older Brothers and Older Sisters Odds Ratios in 36 Samples of Homosexual Males. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:829-832. [PMID: 29396612 DOI: 10.1007/s10508-018-1160-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 01/24/2018] [Indexed: 06/07/2023]
Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada.
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Sabuncuoglu O. Commentary on "Gay Male Only-Children: Evidence for Low Birth Weight and High Maternal Miscarriage Rates" from the Prenatal Thyroid Model Perspective. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:323-325. [PMID: 29204814 DOI: 10.1007/s10508-017-1122-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Osman Sabuncuoglu
- Department of Child and Adolescent Psychiatry, School of Medicine, Marmara University Hospital, Fevzi Cakmak Mah. Muhsin Yazicioglu Cad. No: 10, Pendik, 34899, Istanbul, Turkey.
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17
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Blanchard R. Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:1-15. [PMID: 28608293 DOI: 10.1007/s10508-017-1007-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 06/07/2023]
Abstract
The fraternal birth order effect is the tendency for older brothers to increase the odds of homosexuality in later-born males. This study compared the strength of the effect in subjects from small versus large families and in homosexual subjects with masculine versus feminine gender identities. Meta-analyses were conducted on 30 homosexual and 30 heterosexual groups from 26 studies, totaling 7140 homosexual and 12,837 heterosexual males. The magnitude of the fraternal birth order effect was measured with a novel variable, the Older Brothers Odds Ratio, computed as (homosexuals' older brothers ÷ homosexuals' other siblings) ÷ (heterosexuals' older brothers ÷ heterosexuals' other siblings), where other siblings = older sisters + younger brothers + younger sisters. An Older Brothers Odds Ratio of 1.00 represents no effect of sexual orientation; values over 1.00 are positive evidence for the fraternal birth order effect. Evidence for the reliability of the effect was consistent. The Older Brothers Odds Ratio was significantly >1.00 in 20 instances, >1.00 although not significantly in nine instances, and nonsignificantly <1.00 in 1 instance. The pooled Older Brothers Odds Ratio for all samples was 1.47, p < .00001. Subgroups analyses showed that the magnitude of the effect was significantly greater in the 12 feminine or transgender homosexual groups than in the other 18 homosexual groups. There was no evidence that the magnitude of the effect differs according to family size.
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Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada.
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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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19
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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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20
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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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21
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Abstract
Previous research has indicated that biological older brothers increase the odds of androphilia in males. This finding has been termed the fraternal birth order effect. The maternal immune hypothesis suggests that this effect reflects the progressive immunization of some mothers to male-specific antigens involved in fetal male brain masculinization. Exposure to these antigens, as a result of carrying earlier-born sons, is hypothesized to produce maternal immune responses towards later-born sons, thus leading to female-typical neural development of brain regions underlying sexual orientation. Because this hypothesis posits mechanisms that have the potential to be active in any situation where a mother gestates repeated male fetuses, a key prediction is that the fraternal birth order effect should be observable in diverse populations. The present study assessed the association between sexual orientation and birth order in androphilic male-to-female transsexuals in Brazil, a previously unexamined population. Male-to-female transsexuals who reported attraction to males were recruited from a specialty gender identity service in southern Brazil (n=118) and a comparison group of gynephilic non-transsexual men (n=143) was recruited at the same hospital. Logistic regression showed that the transsexual group had significantly more older brothers and other siblings. These effects were independent of one another and consistent with previous studies of birth order and male sexual orientation. The presence of the fraternal birth order effect in the present sample provides further evidence of the ubiquity of this effect and, therefore, lends support to the maternal immune hypothesis as an explanation of androphilic sexual orientation in some male-to-female transsexuals.
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Abstract
Adolescents presenting with gender-related concerns are increasingly seeking support from providers from a variety of disciplines within health care settings across the world. For those treating young people who meet the criteria for the DSM 5 diagnosis of gender dysphoria (GD), complex decisions in clinical care are common. Defining best practice with this population with respect to interventions that span mental health, physical, and surgical domains can be challenging, given a relative dearth of empirical data available; yet practice guidelines have emerged from different professional organizations which can aid with this. For this review paper, a broad literature search was performed to identify relevant studies pertaining to the care of adolescents with GD. In addition, an overview of trends in clinical practice, including shifts in conceptualization of how clinicians and patients define care that is considered affirming when working with this population, is described. This paper explores the characteristics of referral patterns to specialized clinics, provides a brief overview of gender identity development in adolescence, and then describes the phenomenology of known aetiological factors and co-occurring psychiatric issues in adolescents with GD. Additionally, clinical management considerations that detail assessment aims and common treatment interventions across disciplines will be explored.
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Affiliation(s)
- Scott Leibowitz
- a Ann & Robert H. Lurie Children's Hospital of Chicago , Department of Psychiatry and Behavioral Science, Northwestern Feinberg School of Medicine , Chicago , Illinois
| | - Annelou L C de Vries
- b Departments of Pediatrics, Pediatric Psychology, and Child and Adolescent Psychiatry, Centre of Expertise on Gender Dysphoria , VU University Medical Centre , Amsterdam , Netherlands
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Kishida M, Rahman Q. Fraternal Birth Order and Extreme Right-Handedness as Predictors of Sexual Orientation and Gender Nonconformity in Men. ARCHIVES OF SEXUAL BEHAVIOR 2015; 44:1493-1501. [PMID: 25663238 DOI: 10.1007/s10508-014-0474-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 12/01/2014] [Accepted: 12/06/2014] [Indexed: 06/04/2023]
Abstract
The present study explored whether there were relationships between number of older brothers, handedness, recalled childhood gender nonconformity (CGN), and sexual orientation in men. We used data from previous British studies conducted in our laboratory (N = 1,011 heterosexual men and 921 gay men). These men had completed measures of demographic variables, number and sex of siblings, CGN, and the Edinburgh Handedness Inventory. The results did not replicate the fraternal birth order effect. However, gay men had fewer "other siblings" than heterosexual men (even after controlling for the stopping-rule and family size). In a sub-sample (425 gay men and 478 heterosexual men) with data available on both sibling sex composition and handedness scores, gay men were found to show a significantly greater likelihood of extreme right-handedness and non-right-handedness compared to heterosexual men. There were no significant effects of sibling sex composition in this sub-sample. In a further sub-sample (N = 487) with data available on sibling sex composition, handedness, and CGN, we found that men with feminine scores on CGN were more extremely right-handed and had fewer other-siblings compared to masculine scoring men. Mediation analysis revealed that handedness was associated with sexual orientation directly and also indirectly through the mediating factor of CGN. We were unable to replicate the fraternal birth order effect in our archived dataset but there was evidence for a relationship among handedness, sexual orientation, and CGN. These data help narrow down the number of possible neurodevelopmental pathways leading to variations in male sexual orientation.
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Affiliation(s)
- Mariana Kishida
- Department of Psychology, Institute of Psychiatry, King's College London, 5th Floor, Bermondsey Wing, Guy's Hospital Campus, London, SE1 9RT, UK,
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Blanchard R, VanderLaan DP. Commentary on Kishida and Rahman (2015), Including a Meta-analysis of Relevant Studies on Fraternal Birth Order and Sexual Orientation in Men. ARCHIVES OF SEXUAL BEHAVIOR 2015; 44:1503-1509. [PMID: 25940737 DOI: 10.1007/s10508-015-0555-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada,
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25
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Autism Spectrum Disorder Risk Factors and Autistic Traits in Gender Dysphoric Children. J Autism Dev Disord 2014; 45:1742-50. [DOI: 10.1007/s10803-014-2331-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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VanderLaan DP, Blanchard R, Wood H, Garzon LC, Zucker KJ. Birth weight and two possible types of maternal effects on male sexual orientation: a clinical study of children and adolescents referred to a Gender Identity Service. Dev Psychobiol 2014; 57:25-34. [PMID: 25345970 DOI: 10.1002/dev.21254] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 08/20/2014] [Indexed: 12/12/2022]
Abstract
This study tested predictions regarding two hypothesized maternal immune responses influencing sexual orientation: one affecting homosexual males with high fraternal birth order and another affecting firstborn homosexual individuals whose mothers experience repeated miscarriage after the birth of the first child. Low birth weight was treated as a marker of possible exposure to a maternal immune response during gestation. Birth weight was examined relative to sibship characteristics in a clinical sample of youth (N = 1,722) classified as heterosexual or homosexual based on self-reported or probable sexual orientation. No female sexual orientation differences in birth weight were found. Homosexual, compared to heterosexual, males showed lower birth weight if they had one or more older brothers--and especially two or more older brothers--or if they were an only-child. These findings support the existence of two maternal immune responses influencing male sexual orientation and possibly also cross-gender behavior and identity.
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Affiliation(s)
- Doug P VanderLaan
- Gender Identity Service, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, ON, Canada
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Adults with siblings like children's faces more than those without. J Exp Child Psychol 2014; 129:148-56. [PMID: 25311545 DOI: 10.1016/j.jecp.2014.09.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 09/05/2014] [Accepted: 09/05/2014] [Indexed: 11/22/2022]
Abstract
Humans cross-culturally find infant faces both cute and highly likeable. Their so-called "baby schema" features have clear adaptive value by likely serving as an innate releasing mechanism that elicits caretaking behaviors from adults. However, we do not know whether experience with young children during social development might act to further facilitate this. Here we investigated the potential impact of having siblings on adult likeability judgments of children's faces. In this study, 73 adult men and women (40 with siblings and 33 without) were shown 148 different face pictures of young children (1 month to 6.5 years) and judged them for likeability. Results showed that both groups found faces of infants (<7 months) as equally likeable. However, for faces more than 7 months of age, whereas the no-sibling group showed a reduced liking for faces with increasing age, the sibling group found faces of all ages as equally likeable. Furthermore, for adults with siblings, the closer in age they were to their siblings, the stronger their likeability was for young children's faces. Our results are the first to show that having siblings can extend the influence of baby schema to children as well as infants.
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28
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Blanchard R. Detecting and correcting for family size differences in the study of sexual orientation and fraternal birth order. ARCHIVES OF SEXUAL BEHAVIOR 2014; 43:845-852. [PMID: 24578105 DOI: 10.1007/s10508-013-0245-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/14/2013] [Accepted: 12/14/2013] [Indexed: 06/03/2023]
Abstract
The term "fraternal birth order effect" denotes a statistical relation most commonly expressed in one of two ways: Older brothers increase the odds of homosexuality in later born males or, alternatively, homosexual men tend to have more older brothers than do heterosexual men. The demonstrability of this effect depends partly on the adequate matching of the homosexual and heterosexual study groups with respect to mean family size. If the homosexual group has too many siblings, relative to the heterosexual group, the homosexual group will tend to show the expected excess of older brothers but may also show an excess of other sibling-types (most likely older sisters); if the homosexual group has too few siblings, it will tend not to show a difference in number of older brothers but instead may show a deficiency of other sibling-types (most likely younger brothers and younger sisters). In the first part of this article, these consequences are illustrated with deliberately mismatched groups selected from archived data sets. In the second part, two slightly different methods for transforming raw sibling data are presented. These are intended to produce family-size-corrected variables for each of the four original sibling parameters (older brothers, older sisters, younger brothers, and younger sisters). Both versions are shown to render the fraternal birth order effect observable in the deliberately mismatched groups. In the third part of the article, fraternal birth order studies published in the last 5 years were surveyed for failures to find a statistically significant excess of older brothers for the homosexual group. Two such studies were found in the nine examined. In both cases, the collective findings for older sisters, younger brothers, and younger sisters suggested that the mean family size of the homosexual groups was smaller than that of the heterosexual comparison groups. Furthermore, the individual findings for the four classes of siblings resembled those for the present experimentally mismatched groups in which the mean family size of the homosexual group was significantly smaller. This illustrates the necessity of comparing groups on measures of mean family size and removing this confound in some way when those means are markedly different.
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Affiliation(s)
- Ray Blanchard
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON, M5T 1R8, Canada,
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