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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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Endendijk JJ, Groeneveld MG, Mesman J. The Gendered Family Process Model: An Integrative Framework of Gender in the Family. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:877-904. [PMID: 29549542 PMCID: PMC5891573 DOI: 10.1007/s10508-018-1185-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 05/23/2023]
Abstract
This article reviews and integrates research on gender-related biological, cognitive, and social processes that take place in or between family members, resulting in a newly developed gendered family process (GFP) model. The GFP model serves as a guiding framework for research on gender in the family context, calling for the integration of biological, social, and cognitive factors. Biological factors in the model are prenatal, postnatal, and pubertal androgen levels of children and parents, and genetic effects on parent and child gendered behavior. Social factors are family sex composition (i.e., parent sex, sexual orientation, marriage status, sibling sex composition) and parental gender socialization, such as modeling, gender-differentiated parenting, and gender talk. Cognitive factors are implicit and explicit gender-role cognitions of parents and children. Our review and the GFP model confirm that gender is an important organizer of family processes, but also highlight that much is still unclear about the mechanisms underlying gender-related processes within the family context. Therefore, we stress the need for (1) longitudinal studies that take into account the complex bidirectional relationship between parent and child gendered behavior and cognitions, in which within-family comparisons (comparing behavior of parents toward a boy and a girl in the same family) are made instead of between-family comparisons (comparing parenting between all-boy families and all-girl families, or between mixed-gender families and same-gender families), (2) experimental studies on the influence of testosterone on human gender development, (3) studies examining the interplay between biology with gender socialization and gender-role cognitions in humans.
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Affiliation(s)
- Joyce J Endendijk
- Centre for Child and Family Studies, Leiden University, P.O. Box 9555, 2300 RB, Leiden, The Netherlands
- Child and Adolescent Studies, Utrecht University, P.O. Box 80140, 3508 TC, Utrecht, The Netherlands
| | - Marleen G Groeneveld
- Centre for Child and Family Studies, Leiden University, P.O. Box 9555, 2300 RB, Leiden, The Netherlands
| | - Judi Mesman
- Centre for Child and Family Studies, Leiden University, P.O. Box 9555, 2300 RB, Leiden, The Netherlands.
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Wampold CH. Volvivity, Femininity, Fraternity: Breaching the Sexual Orientation Fortress. ARCHIVES OF SEXUAL BEHAVIOR 2018; 47:43-46. [PMID: 29071545 DOI: 10.1007/s10508-017-1101-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/11/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Charles H Wampold
- Collaborative Research Group on Health Policy and Promotion, York College of the City University of New York, Jamaica, NY, USA.
- , 41 South Harrison Street, Princeton, NJ, 08540, USA.
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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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Bozkurt A, Bozkurt OH, Sonmez I. Birth Order and Sibling Sex Ratio in a Population with High Fertility: Are Turkish Male to Female Transsexuals Different? ARCHIVES OF SEXUAL BEHAVIOR 2015; 44:1331-1337. [PMID: 25351529 DOI: 10.1007/s10508-014-0425-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/03/2014] [Accepted: 10/03/2014] [Indexed: 06/04/2023]
Abstract
Western studies have consistently found that androphilic (sexually attracted to men) male-to-female transsexuals have a later birth order and a relative excess of brothers compared with appropriate control participants. However, non-Western studies on birth order and sibling sex ratio in androphilic males (transsexual or non-transsexual) are rare. The objective of the study was to test the hypothesis that androphilic male-to-female transsexuals have a late birth order and a relative excess of brothers in a non-Western culture with a higher fertility rate. The participants were 60 androphilic male-to-female transsexuals and 61 male heterosexual controls. The transsexual participants had significantly more older brothers than the control participants, but the groups did not differ in their numbers of older sisters, younger brothers, or younger sisters. The foregoing pattern is usually referred to as the "fraternal birth order effect." Slater's and Berglin's Indexes both showed that the mean birth order of the control participants was very close to that expected from a random sample drawn from a demographically stable population whereas the mean birth order of the transsexual participants was later. A measure of sibship composition, brothers/all siblings, showed that the transsexual group had a higher proportion of male siblings compared with the control group. In conclusion, the present study found that Turkish androphilic male-to-female transsexuals show the same high fraternal birth order that has been found in comparable androphilic samples in Western Europe, North America, and the South Pacific, which suggests a common underlying biological causal mechanism.
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Affiliation(s)
- Ali Bozkurt
- Department of Psychiatry, School of Medicine, Near East University, Near East Boulevard, Nicosia-TRNC, Mersin 10, Turkey,
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Firth MT. Childhood abuse, depressive vulnerability and gender dysphoria: Part 2. COUNSELLING & PSYCHOTHERAPY RESEARCH 2015. [DOI: 10.1002/capr.12002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Malcolm T. Firth
- Psychological Services; Manchester Mental Health NHS and Social Care Trust; Manchester UK
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VanderLaan DP, Postema L, Wood H, Singh D, Fantus S, Hyun J, Leef J, Bradley SJ, Zucker KJ. Do children with gender dysphoria have intense/obsessional interests? JOURNAL OF SEX RESEARCH 2015; 52:213-9. [PMID: 24558954 DOI: 10.1080/00224499.2013.860073] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This study examined whether children clinically referred for gender dysphoria (GD) show increased symptoms of autism spectrum disorder (ASD). Circumscribed preoccupations or intense interests were considered as overlapping symptoms expressed in GD and ASD. In gender-referred children (n = 534; 82.2% male) and their siblings (n = 419; 57.5% male), we examined Items 9 and 66 on the Child Behavior Checklist, which measure obsessions and compulsions, respectively. Non-GD clinic-referred (n = 1,201; 48.5% male) and nonreferred (n = 1,201; 48.5% male) children were also examined. Gender-referred children were elevated compared to all other groups for Item 9, and compared to siblings and nonreferred children for Item 66. A gender-related theme was significantly more common for gender-referred boys than male siblings on Item 9 only. A gender-related theme was not significantly more common for gender-referred girls compared to their female siblings on either item. The findings for Item 9 support the idea that children with GD show an elevation in obsessional interests. For gender-referred boys in particular, gender-related themes constituted more than half of the examples provided by their mothers. Intense/obsessional interests in children with GD may be one of the factors underlying the purported link between GD and ASD.
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Affiliation(s)
- Doug P VanderLaan
- a Gender Identity Service, Child, Youth, and Family Services, Centre for Addiction and Mental Health
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8
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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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VanderLaan DP, Blanchard R, Wood H, Zucker KJ. Birth order and sibling sex ratio of children and adolescents referred to a gender identity service. PLoS One 2014; 9:e90257. [PMID: 24651045 PMCID: PMC3961213 DOI: 10.1371/journal.pone.0090257] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 01/30/2014] [Indexed: 01/29/2023] Open
Abstract
In adult male samples, homosexuality is associated with a preponderance of older brothers (i.e., the fraternal birth order effect). In several studies comparing gender dysphoric youth, who are likely to be homosexual in adulthood, to clinical or non-clinical control groups, the findings have been consistent with the fraternal birth order effect in males; however, less is known about unique sibship characteristics of gender dysphoric females. The current study investigated birth order and sibling sex ratio in a large sample of children and adolescents referred to the same Gender Identity Service (N = 768). Probands were classified as heterosexual males, homosexual males, or homosexual females based on clinical diagnostic information. Groups differed significantly in age and sibship size, and homosexual females were significantly more likely to be only children. Subsequent analyses controlled for age and for sibship size. Compared to heterosexual males, homosexual males had a significant preponderance of older brothers and homosexual females had a significant preponderance of older sisters. Similarly, the older sibling sex ratio of homosexual males showed a significant excess of brothers whereas that of homosexual females showed a significant excess of sisters. Like previous studies of gender dysphoric youth and adults, these findings were consistent with the fraternal birth order effect. In addition, the greater frequency of only children and elevated numbers of older sisters among the homosexual female group adds to a small literature on sibship characteristics of potential relevance to the development of gender identity and sexual orientation in females.
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Affiliation(s)
- Doug P. VanderLaan
- Gender Identity Service, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, Canada
| | - Ray Blanchard
- Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Hayley Wood
- Gender Identity Service, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, Canada
| | - Kenneth J. Zucker
- Gender Identity Service, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, Canada
- Department of Psychiatry, University of Toronto, Toronto, Canada
- * E-mail:
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Zucker KJ, Cohen-Kettenis PT, Drescher J, Meyer-Bahlburg HFL, Pfäfflin F, Womack WM. Memo outlining evidence for change for gender identity disorder in the DSM-5. ARCHIVES OF SEXUAL BEHAVIOR 2013; 42:901-14. [PMID: 23868018 DOI: 10.1007/s10508-013-0139-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- Kenneth J Zucker
- Gender Identity Service, Child, Youth, and Family Services, Underserved Populations Program, Centre for Addiction and Mental Health, 80 Workman Way, Toronto, ON, M6J 1H4, Canada.
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Schagen SEE, Delemarre-van de Waal HA, Blanchard R, Cohen-Kettenis PT. Sibling sex ratio and birth order in early-onset gender dysphoric adolescents. ARCHIVES OF SEXUAL BEHAVIOR 2012; 41:541-9. [PMID: 21674256 PMCID: PMC3338001 DOI: 10.1007/s10508-011-9777-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 04/16/2011] [Accepted: 04/30/2011] [Indexed: 05/26/2023]
Abstract
Several sibship-related variables have been studied extensively in sexual orientation research, especially in men. Sibling sex ratio refers to the ratio of brothers to sisters in the aggregate sibships of a group of probands. Birth order refers to the probands' position (e.g., first-born, middle-born, last-born) within their sibships. Fraternal birth order refers to their position among male siblings only. Such research was extended in this study to a large group of early-onset gender dysphoric adolescents. The probands comprised 94 male-to-female and 95 female-to-male gender dysphoric adolescents. The overwhelming majority of these were homosexual or probably prehomosexual. The control group consisted of 875 boys and 914 girls from the TRAILS study. The sibling sex ratio of the gender dysphoric boys was very high (241 brothers per 100 sisters) compared with the expected ratio (106:100). The excess of brothers was more extreme among the probands' older siblings (300:100) than among their younger siblings (195:100). Between-groups comparisons showed that the gender dysphoric boys had significantly more older brothers, and significantly fewer older sisters and younger sisters, than did the control boys. In contrast, the only notable finding for the female groups was that the gender dysphoric girls had significantly fewer total siblings than did the control girls. The results for the male probands were consistent with prior speculations that a high fraternal birth order (i.e., an excess of older brothers) is found in all homosexual male groups, but an elevated sibling sex ratio (usually caused by an additional, smaller excess of younger brothers) is characteristic of gender dysphoric homosexual males. The mechanisms underlying these phenomena remain unknown.
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Affiliation(s)
- Sebastian E. E. Schagen
- Department of Pediatric Endocrinology, VU University Medical Centre, Amsterdam, The Netherlands
| | - Henriette A. Delemarre-van de Waal
- Department of Pediatric Endocrinology, VU University Medical Centre, Amsterdam, The Netherlands
- Department of Pediatrics, LUMC University Hospital Leiden, Leiden, The Netherlands
| | - Ray Blanchard
- Law and Mental Health Program, Centre for Addiction and Mental Health, Toronto, ON Canada
| | - Peggy T. Cohen-Kettenis
- Department of Medical Psychology and Medical Social Work, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam, The Netherlands
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Gómez-Gil E, Esteva I, Carrasco R, Almaraz MC, Pasaro E, Salamero M, Guillamon A. Birth order and ratio of brothers to sisters in Spanish transsexuals. ARCHIVES OF SEXUAL BEHAVIOR 2011; 40:505-510. [PMID: 20232130 DOI: 10.1007/s10508-010-9614-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 02/09/2010] [Accepted: 02/13/2010] [Indexed: 05/28/2023]
Abstract
Three Western studies have shown that male-to-female (MF) homosexual transsexuals tend to be born later than their siblings and to come from sibships with more brothers than sisters. The objective of this study was to determine whether these variables would be replicated in 530 MF and female-to-male (FM) Spanish transsexuals according to sexual orientation. The results showed that MF homosexual transsexuals had significantly more older brothers than the non-homosexual MF group. Compared with the expected rates in the general population, birth order was significantly higher in both MF (Slater's Index = 0.59; Fraternal Index = 0.61; Sororal Index = 0.58) and FM homosexual transsexuals (Slater's Index = 0.65; Fraternal Index = 0.68; Sororal Index = 0.67), and sibling sex ratio was significantly higher than expected in homosexual MF (sex ratio = 0.55) but not in homosexual FM transsexuals. No significant differences were found in the non-homosexual subgroups. The replication of the later birth order and sibling sex-ratio effect in MF homosexual transsexuals corroborates previous findings in a variety of groups from different cultures and may suggest a common mechanism underlying the etiology of transsexualism.
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Affiliation(s)
- Esther Gómez-Gil
- Unidad de Identidad de Género, Instituto Clínic de Neurociencias, Servicio de Psiquiatría, Hospital Clínic, Universidad de Barcelona, Spain.
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de Medeiros CB, Rees SL, Llinas M, Fleming AS, Crews D. Deconstructing Early Life Experiences. Psychol Sci 2010; 21:1494-501. [DOI: 10.1177/0956797610382122] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In rodents, a pup’s experiences in utero and during postnatal development shape its sexual behavior as an adult and how it is perceived by potential mates. We show that the male rat’s sexuality is primarily influenced by the postnatal sex ratio of its litter, but not by the litter’s prenatal intrauterine sex ratio or the behavior of its mother. Pups from litters with differing prenatal sex ratios were divided into litters with differing postnatal sex ratios. We found that males raised in a female-biased litter exhibited less mounting than males raised in either a male-biased litter or one with an equal sex ratio, and were less attractive to sexually receptive females, eliciting fewer soliciting behaviors, such as hop-darts, and fewer lordosis behaviors. However, the number of intromissions and ejaculations did not differ across groups, which suggests that males from female-biased litters mate as efficiently as males raised in other sex ratios, but do not require as many mounts to do so. The reported differences in sexual behavior did not vary with the quality of maternal behavior or with sexual experience in adulthood.
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Affiliation(s)
| | | | - Maheleth Llinas
- Department of Psychology, University of Toronto at Mississauga
| | | | - David Crews
- Section of Integrative Biology, University of Texas at Austin
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Carvalho IP. Two Siblings Concordant for Male-to-Female Transsexualism: A Case Report. INT J TRANSGENDERISM 2010. [DOI: 10.1080/15532731003688954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Bockting W. Are Gender Identity Disorders Mental Disorders? Recommendations for Revision of the World Professional Association for Transgender Health'sStandards of Care. Int J Transgend 2009. [DOI: 10.1080/15532730902799987] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Blanchard R, Lippa RA. The sex ratio of older siblings in non-right-handed homosexual men. ARCHIVES OF SEXUAL BEHAVIOR 2008; 37:970-6. [PMID: 17131198 DOI: 10.1007/s10508-006-9107-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 08/11/2006] [Accepted: 08/11/2006] [Indexed: 05/12/2023]
Abstract
This study tested the prediction, based on prior research, that non-right-handed homosexual men will report fewer than expected older brothers. Participants were 2486 heterosexual and homosexual, right-handed and non-right-handed, male and female adults, representing five samples collected for various projects by the second author. Data on sibship composition, sexual orientation, and hand-preference were gathered in the original research using on-line (Internet) or self-administered paper-and-pencil questionnaires. The non-right-handed homosexual men reported 83 older brothers per 100 older sisters, which was significantly lower than the human sex ratio of 106 live-born males per 100 live-born females. In contrast, the right-handed homosexual men reported 125 older brothers per 100 older sisters, which was significantly higher than the expected ratio. One possible explanation of these results is that older brothers increase the odds of homosexuality in right-handed males but decrease the odds of homosexuality in non-right-handed males. A second possibility is that older brothers decrease the probability that non-right-handed homosexual males will be represented in survey research. The latter scenario could arise if the combination of some biological factor associated with older brothers and some biological factor associated with non-right-handedness is so toxic that it kills the fetus or predisposes the individual to a condition (e.g., mental retardation, major mental illness) that makes him less likely to be available for research recruitment at Gay Pride parades (etc.) than other members of the gay community.
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Affiliation(s)
- Ray Blanchard
- Law and Mental Health Program, Centre for Addiction and Mental Health, College Street Site, 250 College Street, Toronto, Ontario, M5T 1R8, Canada.
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Langevin R, Langevin M, Curnoe S. Family size, birth order, and parental age among male paraphilics and sex offenders. ARCHIVES OF SEXUAL BEHAVIOR 2007; 36:599-609. [PMID: 17186126 DOI: 10.1007/s10508-006-9110-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A sample of 1823 male paraphilics, sex offenders, and non-sex offender controls were compared on family size, birth order, and parents' ages at the time of the probands' births. Sample data were also compared to population data from Statistics Canada. The men in all groups were from larger than average Canadian families and they tended to be later born. Paraphilics and sex offenders had even larger families than offender controls. Their parents tended to be older at their birth with 34.2% of mothers and 51.3% of fathers over 30 years of age, but there were no statistically significant subgroup differences. There were also significantly more multiparous teenage mothers than expected and more paraphilics' fathers who were younger than the mothers, both factors associated in the literature with increased risk of perinatal complications and abnormalities. The confounding influences of parental age, birth order, and family size were examined and indicated the need for large samples and multivariate analysis in evaluating the role of family variables associated with paraphilics and sex offenders.
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Affiliation(s)
- Ron Langevin
- Juniper Associates, 5468 Dundas Street West, Suite 402, Etobicoke, Ontario, M9B 6E3, Canada.
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Blanchard R, Cantor JM, Bogaert AF, Breedlove SM, Ellis L. Interaction of fraternal birth order and handedness in the development of male homosexuality. Horm Behav 2006; 49:405-14. [PMID: 16246335 DOI: 10.1016/j.yhbeh.2005.09.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 09/08/2005] [Accepted: 09/12/2005] [Indexed: 11/20/2022]
Abstract
The present study investigated evidence for an interaction between two of the best established etiologic factors, or markers of etiologic factors, in the literature on male homosexuality: fraternal birth order and hand preference. By combining five samples, the authors produced study groups of 1774 right-handed heterosexuals, 287 non-right-handed heterosexuals, 928 right-handed homosexuals, and 157 non-right-handed homosexuals. The results showed a significant (P = 0.004) handedness by older brothers interaction, such that (a) the typical positive correlation between homosexuality and greater numbers of older brothers holds only for right-handed males, (b) among men with no older brothers, homosexuals are more likely to be non-right-handed than heterosexuals; among men with one or more older brothers, homosexuals are less likely to be non-right-handed than heterosexuals, and (c) the odds of homosexuality are higher for men who have a non-right hand preference or who have older brothers, relative to men with neither of these features, but the odds for men with both features are similar to the odds for men with neither. These findings have at least two possible explanations: (a) the etiologic factors associated with non-right-handedness and older brothers-hypothesized to be hyperandrogenization and anti-male antibodies, respectively-counteract each other, yielding the functional equivalent of typical masculinization, and (b) the number of non-right-handed homosexuals with older brothers is smaller than expected because the combination of the older brothers factor with the non-right-handedness factor is toxic enough to lower the probability that the affected fetus will survive.
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Affiliation(s)
- Ray Blanchard
- Law and Mental Health Program, Centre for Addiction and Mental Health, Toronto, ON, Canada.
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Bogaert AF. Gender role/identity and sibling sex ratio in homosexual men. JOURNAL OF SEX & MARITAL THERAPY 2005; 31:217-27. [PMID: 16020140 DOI: 10.1080/00926230590513438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Previous research has suggested that homosexual men's sibling sex ratio-the ratio of brothers to sisters collectively reported by a group of individuals-is elevated but only in samples of extremely feminine (e.g., transsexual) homosexual men. I conducted an additional test of a sibling sex ratio effect in a general sample of homosexual men (N = 237), and examined the correlation between sibling sex ratio and childhood gender identity. I found no significant effects. My discussion focuses on why little evidence of a relationship between sibling sex ratio and cross-gender behavior in childhood occurs within this general sample of homosexual men when samples selected for very feminine homosexual men have detected an elevated sibling sex ratio.
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Affiliation(s)
- Anthony F Bogaert
- Department of Community Health Sciences, Brock University, St.Catharines, Canada.
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Bogaert AF. Sibling sex ratio and sexual orientation in men and women: new tests in two national probability samples. ARCHIVES OF SEXUAL BEHAVIOR 2005; 34:111-116. [PMID: 15772774 DOI: 10.1007/s10508-005-1005-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Revised: 08/04/2004] [Accepted: 08/07/2004] [Indexed: 05/24/2023]
Abstract
One line of research on the etiology of sexual orientation has examined sibling sex ratio, the ratio of brothers to sisters collectively reported by a group of individuals, but this research has only used clinical and/or convenience samples. In the present study, homosexual men and women's sibling sex ratio was examined in two national probability samples. Results indicated that homosexual men had a sex ratio of 129.54 male live births to 100 female live births. This ratio was within the range of elevated sex ratios found in some previous studies of homosexual men, although it was only marginally significant (p = .09) relative to the known human sex ratio with regard to live births. Additional analyses indicated that this effect was likely the result of a high fraternal birth order (i.e., an elevated number of older brothers) in homosexual men. The sibling sex ratio for lesbians was 122.58 male live births to 100 female live births, which did not significantly differ from the known human sex ratio with regard to live births. The results for lesbians, however, should be interpreted with caution because the sample size (and resulting power) was low. The results in men add to research suggesting that homosexual men, unselected for gender identity or gender role behavior, do not have elevated sibling sex ratios. These results also suggest that research should concentrate on finding the cause(s) of the fraternal birth order effect, the consistent finding that homosexual men have an elevated number of older brothers.
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Affiliation(s)
- Anthony F Bogaert
- Departments of Community Health Sciences and Department of Psychology, Brock University, St. Catharines, Ontario, Canada.
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Abstract
This article focuses on the psychosexual development of children and adolescents who have sex-typed behavioral patterns that correspond to the diagnosis of Gender Identity Disorder, as defined in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. The author provides an update on phenomenology and diagnosis, associated behavior problems, developmental course, biologic and psychosocial influences, and treatment and ethical issues.
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Affiliation(s)
- Kenneth J Zucker
- Child and Adolescent Gender Identity Clinic, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
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Poasa KH, Blanchard R, Zucker KJ. Birth order in transgendered males from Polynesia: a quantitative study of Samoan fa'afāfine. JOURNAL OF SEX & MARITAL THERAPY 2004; 30:13-23. [PMID: 14660290 DOI: 10.1080/00926230490247110] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In previous research, a late birth order has been shown to be a characteristic of Western homosexual transsexual men. To date, however, it is not clear if a late birth order is specific to Western transsexuals or may be a characteristic of non-Western transgendered males as well. We quantified birth order in a sample of 13 transgendered males known as fa'afāfine from Samoa. On average, the fa'afāfine were late born, both with regard to number of older brothers and number of older sisters, although the effect appeared to be somewhat stronger with regard to number of older brothers. We consider possible interpretations of the late birth order effect, along with recommendations for further research to identify common mechanisms that might underlie transgenderism across different cultural groups.
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Affiliation(s)
- Kris H Poasa
- Department of Psychology and Professional Counseling, Northwest Christian College, Eugene, Oregon
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Affiliation(s)
- Kenneth J Zucker
- Child and Adolescent Gender Identity Clinic, Child Psychiatry Program, Center for Addiction and Mental Health-Clarke Division, Toronto, Ontario, Canada.
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Hines M, Johnston KJ, Golombok S, Rust J, Stevens M, Golding J. Prenatal stress and gender role behavior in girls and boys: a longitudinal, population study. Horm Behav 2002; 42:126-34. [PMID: 12367566 DOI: 10.1006/hbeh.2002.1814] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prenatal stress influences neural and behavioral sexual differentiation in rodents. Male offspring of stressed pregnancies show reduced masculine-typical characteristics and increased feminine-typical characteristics, whereas female offspring show the opposite pattern, reduced feminine-typical and increased masculine-typical characteristics. These outcomes resemble those seen following manipulations of gonadal hormones and are thought to occur because stress influences these hormones during critical periods of development. Research on prenatal stress and human sexual differentiation has produced inconsistent results, perhaps because studies have used small samples and assessed prenatal stress retrospectively. We related maternal self-reports of prenatal stress to childhood gender role behavior in a prospective, population study of 13,998 pregnancies resulting in 14,138 offspring. Neither stress reported during the first 18 weeks of pregnancy nor stress reported from week 19 of pregnancy to week 8 postnatal related to gender role behavior in male offspring at the age of 42 months. In female offspring, maternal reports of stress during both periods showed only small correlations with masculine-typical behavior. Although this relationship remained significant when other factors that related to stress were controlled, these other factors made larger contributions to girls' gender role behavior than did prenatal stress. In addition, in both boys and girls, older male or female siblings, parental adherence to traditional sex roles, maternal use of tobacco or alcohol during pregnancy, and maternal education all related significantly to gender role behavior. Our results suggest that prenatal stress does not influence the development of gender role behavior in boys and appears to have relatively little, if any, influence on gender role behavior in girls.
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Affiliation(s)
- Melissa Hines
- Department of Psychology, City University, London, United Kingdom.
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Blanchard R, Zucker KJ, Cavacas A, Allin S, Bradley SJ, Schachter DC. Fraternal birth order and birth weight in probably prehomosexual feminine boys. Horm Behav 2002; 41:321-7. [PMID: 11971666 DOI: 10.1006/hbeh.2002.1765] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to confirm a previous finding that homosexual males with older brothers weigh less at birth than do heterosexual males with older brothers. The subjects comprised 250 feminine boys referred to a child psychiatry service because of extreme cross-gender wishes or behavior and assumed, on the basis of previous research, to be prehomosexual, plus 739 control boys and 261 control girls referred to the same service for reasons unrelated to sexual orientation or gender identity disorder and assumed, from base-rate probabilities, to be preheterosexual. The feminine boys with two or more older brothers weighed 385 g less at birth than did the control boys with two or more older brothers (P = 0.005). In contrast, the feminine and control boys with fewer than two older brothers did not differ in birth weight. This finding suggests that the mechanism by which older brothers increase the odds of homosexuality in later-born males operates prior to the individual's birth. We hypothesize that this mechanism may be immunologic, that antimale antibodies produced by human mothers in response to immunization by male fetuses could decrease the birth weight of subsequent male fetuses as well as increase their odds of homosexuality.
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Affiliation(s)
- Ray Blanchard
- Centre for Addiction and Mental Health-Clarke Site, 250 College Street, Toronto, Ontario, Canada M5T 1R8.
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Abstract
In men, sexual orientation correlates with an individual's number of older brothers, each additional older brother increasing the odds of homosexuality by approximately 33%. It has been hypothesized that this fraternal birth order effect reflects the progressive immunization of some mothers to Y-linked minor histocompatibility antigens (H-Y antigens) by each succeeding male fetus and the concomitantly increasing effects of such maternal immunization on the future sexual orientation of each succeeding male fetus. According to this hypothesis, anti-H-Y antibodies produced by the mother pass through the placental barrier to the fetus and affect aspects of sexual differentiation in the fetal brain. This explanation is consistent with a variety of evidence, including the apparent irrelevance of older sisters to the sexual orientation of later born males, the probable involvement of H-Y antigen in the development of sex-typical traits, and the detrimental effects of immunization of female mice to H-Y antigen on the reproductive performance of subsequent male offspring. The maternal immune hypothesis might also explain the recent finding that heterosexual males with older brothers weigh less at birth than heterosexual males with older sisters and homosexual males with older brothers weigh even less than heterosexual males with older brothers.
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Affiliation(s)
- R Blanchard
- Centre for Addiction and Mental Health-Clarke Site, Department of Psychiatry, Faculty of Medicine, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada.
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