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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Recent research suggests that only-child gay men might owe their sexual orientation to maternal immune processes that are not related to the fraternal birth order effect (Blanchard, 2012; Skorska, Blanchard, VanderLaan, Zucker, & Bogaert, 2017; VanderLaan et al., 2015). As such, we also performed our analyses with only children removed; however, doing so had no impact on the statistical significance of the findings reported here. We, therefore, present the analyses with only children retained.
References
Bailey, J. M. (2003). The man who would be queen: The science of gender-bending and transsexualism. Washington, DC: Joseph Henry Press.
Bearman, P. S., & Bruckner, H. (2002). Opposite-sex twins and adolescent same-sex attraction. American Journal of Sociology, 107, 1179–1205.
Berglin, C. G. (1982). Birth order as a quantitative expression of date of birth. Journal of Epidemiology and Community Health, 36, 298–302.
Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual versus heterosexual males and females. Annual Review of Sex Research, 8, 27–67.
Blanchard, R. (2004). Quantitative and theoretical analyses of the relation between older brothers and homosexuality in men. Journal of Theoretical Biology, 230, 173–187.
Blanchard, R. (2012). A possible second type of maternal–fetal immune interaction involved in both male and female homosexuality. Archives of Sexual Behavior, 41, 1507–1511.
Blanchard, R. (2014). Detecting and correcting for family size differences in the study of sexual orientation and fraternal birth order. Archives of Sexual Behavior, 43, 845–852.
Blanchard, R., & Bogaert, A. F. (1996). Homosexuality in men and number of older brothers. American Journal of Psychiatry, 153, 27–31.
Blanchard, R., & Ellis, L. (2001). Birth weight, sexual orientation and the sex of preceding siblings. Journal of Biosocial Science, 33, 45–467.
Blanchard, R., & Klassen, P. (1997). H-Y antigen and homosexuality in men. Journal of Theoretical Biology, 185, 373–378.
Blanchard, R., & Sheridan, P. M. (1992). Sibship size, sibling sex ratio, birth order, and parental age in homosexual and nonhomosexual gender dysphorics. Journal of Nervous and Mental Disease, 180, 40–47.
Blanchard, R., & VanderLaan, D. P. (2015). 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, 44, 1503–1509.
Blanchard, R., Zucker, K. J., Bradley, S. J., & Hume, C. S. (1995). Birth order and sibling sex ratio in homosexual male adolescents and probably prehomosexual feminine boys. Developmental Psychology, 31, 22–30.
Blanchard, R., Zucker, K. J., Cavacas, A., Allin, S., Bradley, S. J., & Schachter, D. C. (2002). Fraternal birth order and birth weight in probably prehomosexual feminine boys. Hormones and Behavior, 41, 321–327.
Blanchard, R., Zucker, K. J., Cohen-Kettenis, P. T., Gooren, L. J., & Bailey, J. M. (1996). Birth order and sibling sex ratio in two samples of Dutch gender-dysphoric homosexual males. Archives of Sexual Behavior, 25, 495–514.
Bogaert, A. F. (2003). Number of older brothers and social orientation: New tests and the attraction/behavior distinction in two national probability samples. Journal of Personality and Social Psychology, 84, 644–652.
Bogaert, A. F. (2006). Biological versus nonbiological older brothers and men’s sexual orientation. Proceedings of the National Academy of Science United States of America, 103, 10771–10774.
Bogaert, A. F., Friesen, C., & Klentrou, P. (2002). Age of puberty and sexual orientation in a national probability sample. Archives of Sexual Behavior, 31, 73–81.
Bogaert, A. F., & Skorska, M. (2011). Sexual orientation, fraternal birth order, and the maternal immune hypothesis: A review. Frontiers of Neuroendocrinology, 32, 247–254.
Bozkurt, A., Bozkurt, O. H., & Sonmez, I. (2015). Birth order and sibling sex ratio in a population with high fertility: Are Turkish male to female transsexuals different? Archives of Sexual Behavior, 44, 1331–1337.
Cohen, K. M. (2002). Relationships among childhood sex-atypical behavior, spatial ability, handedness, and sexual orientation in men. Archives of Sexual Behavior, 31, 129–143.
Currin, J. M., Gibson, L., & Hubach, R. D. (2015). Multidimensional assessment of sexual orientation and the fraternal birth order effect. Psychology of Sexual Orientation and Gender Diversity, 2, 113–122.
Francis, A. M. (2008). Family and sexual orientation: The family-demographic correlates of homosexuality in men and women. Journal of Sex Research, 45, 371–377.
Frisch, M., & Hviid, A. (2006). Childhood family correlates of heterosexual and homosexual marriages: A national cohort study of two million Danes. Archives of Sexual Behavior, 35, 533–547.
Gomez-Gil, E., Esteva, I., Carrasco, R., Almaraz, M. C., Pasaro, E., Salamero, M., & Guillamon, A. (2011). Birth order and ratio of brothers to sisters in Spanish transsexuals. Archives of Sexual Behavior, 40, 505–510.
Green, R. (2000). Birth order and ratio of brothers to sisters in transsexuals. Psychological Medicine, 30, 789–795.
James, W. H. (2004). The cause(s) of the fraternal birth order effect in male homosexuality. Journal of Biosocial Science, 36, 51–59.
Jones, M. B., & Blanchard, R. (1998). Birth order and male homosexuality: Extension of Slater’s index. Human Biology, 70, 775–787.
Kangassalo, K., Polkki, M., & Rantala, M. J. (2011). Prenatal influences on sexual orientation: Digit ratio (2D:4D) and number of older siblings. Evolutionary Psychology, 9, 496–508.
King, M., Green, J., Osborn, D. P. J., Arkell, J., Hetherton, J., & Pereira, E. (2005). Family size in white gay and heterosexual men. Archives of Sexual Behavior, 34, 117–122.
Kishida, M., & Rahman, Q. (2015). Fraternal birth order and extreme right-handedness as predictors of sexual orientation and gender nonconformity in men. Archives of Sexual Behavior, 44, 1493–1501.
Lippa, R. (1998). Gender-related individual difference and the structure of vocational interests: The importance of the “People-Things” dimension. Journal of Personality and Social Psychology, 74, 996–1009.
Lippa, R. A. (2010). Sex differences in personality traits and gender-related occupational preferences across 53 nations: Testing evolutionary and social-environmental theories. Archives of Sexual Behavior, 39, 619–636.
Moskowitz, D. A., & Hart, T. A. (2011). The influence of physical body traits and masculinity on anal sex roles in gay and bisexual men. Archives of Sexual Behavior, 40, 835–841.
Pachankis, J. E., Buttenwieser, I. G., Bernstein, L. B., & Bayles, K. O. (2013). A longitudinal, mixed methods study of sexual position identity, behavior, and fantasies among young sexual minority men. Archives of Sexual Behavior, 42, 1241–1253.
Rahman, Q. (2005). The association between the fraternal birth order effect in male homosexuality and other markers of human sexual orientation. Biology Letters, 1, 393–395.
Savin-Williams, R. C. (2017). An exploratory study of exclusively heterosexual, primarily heterosexual, and mostly heterosexual young men. Sexualities. doi:10.1177/1363460716678559.
Schagen, S. E., Delemarre-van de Waal, H. A., Blanchard, R., & Cohen- Kettenis, P. T. (2012). Sibling sex ratio and birth order in early- onset gender dysphoric adolescents. Archives of Sexual Behavior, 41, 541–549.
Schwartz, G., Kim, R. M., Kolundzija, A. B., Rieger, G., & Sanders, A. R. (2010). Biodemographic and physical correlates of sexual orientation in men. Archives of Sexual Behavior, 39, 93–109.
Skorska, M. N., Blanchard, R., VanderLaan, D. P., Zucker, K. J., & Bogaert, A. F. (2017). Gay male only-children: Evidence for low birth weight and high maternal miscarriage rates. Archives of Sexual Behavior, 46, 205–215.
Tskhay, K. O., & Rule, N. O. (2013). Accurate identification of a preference for insertive versus receptive intercourse from static facial cues of gay men. Archives of Sexual Behavior, 42, 1217–1222.
VanderLaan, D. P., Blanchard, R., Wood, H., Garzon, L. C., & Zucker, K. J. (2015). 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. Developmental Psychobiology, 57, 25–34.
VanderLaan, D. P., Blanchard, R., Wood, H., & Zucker, K. J. (2014). Birth order and sibling sex ratio of children and adolescents referred to a gender identity service. PLoS ONE, 9, e90257. doi:10.1371/journal.pone.0090257.
VanderLaan, D. P., Blanchard, R., Zucker, K. J., Massuda, R., Vaitses Fontanari, A. M., Oliviera Borba, A., … Lobato, M. I. R. (2016). Birth order and androphilic male-to-female transsexualism in Brazil. Journal of Biosocial Science. doi:10.1017/S0021932016000584.
VanderLaan, D. P., & Vasey, P. L. (2011). Male sexual orientation in Independent Samoa: Evidence for fraternal birth order and maternal fecundity effects. Archives of Sexual Behavior, 40, 495–503.
Wampold, C. H. (2013). Redesigning fraternal birth order studies from top to bottom [Letter to the Editor]. Archives of Sexual Behavior, 42, 1387–1389.
Weinrich, J. D., Grant, I., Jacobson, D. L., Robinson, S. R., McCutchan, J. A., & HNRC Group. (1992). Effects of recalled childhood gender nonconformity on adult genitoerotic role and AIDS exposure. Archives of Sexual Behavior, 21, 559–585.
Whitehead, N. E. (2007). An antiboy antibody? Re-examination of the maternal immune hypothesis. Journal of Biosocial Science, 39, 905–921.
Zheng, L., Hart, T. A., & Zheng, Y. (2012). The relationship between intercourse preference positions and personality traits among gay men in China. Archives of Sexual Behavior, 41, 683–689.
Zheng, L., Hart, T. A., & Zheng, Y. (2013). Attraction to male facial masculinity in gay men in China: Relationship to intercourse preference positions and sociosexual behavior. Archives of Sexual Behavior, 42, 1223–1232.
Zheng, L., Hart, T. A., & Zheng, Y. (2015). Top/bottom sexual self-labels and empathizing-systemizing cognitive styles among gay men in China. Archives of Sexual Behavior, 44, 1431–1438.
Zucker, K. J., Mitchell, J. N., Bradley, S. J., Tkachuk, J., Cantor, J. M., & Allin, S. M. (2006). The Recalled Childhood Gender Identity/Gender Role Questionnaire: Psychometric properties. Sex roles, 54, 469–483.
Acknowledgements
We would like to thank all our volunteers who assisted in participant recruitment at the Toronto Pride Festival (Mary Loka, Lindsay Melhuish, Phil Nguyen, Lauren Oakley, Martha Pokarowski, Firyal Ramzan, Anna Takagi, and Robert Wither). The research reported in this article was supported by a doctoral Canada Graduate Scholarship from the National Sciences and Engineering Research Council of Canada (NSERC) and an Ontario Graduate Scholarship to ASG, as well as by NSERC Discovery Grants to DAM and DPV.
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Swift-Gallant, A., Coome, L.A., Monks, D.A. et al. Gender Nonconformity and Birth Order in Relation to Anal Sex Role Among Gay Men. Arch Sex Behav 47, 1041–1052 (2018). https://doi.org/10.1007/s10508-017-0980-y
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DOI: https://doi.org/10.1007/s10508-017-0980-y