The association between the fraternal birth order effect in male homosexuality and other markers of human sexual orientation

Rahman, Qazi

doi:10.1098/rsbl.2005.0342

Cited by 13 publications

(10 citation statements)

References 19 publications

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“…A number of studies have explored the relationships between older siblings and the birth weight of later‐born neonate (Blanchard and Ellis, 2001; Cote et al, 2003; Magnus et al, 1985; Puts et al, 2006; Rahman, 2005; Rickard et al, 2007; Trotnow et al, 1976). Two of them have found that a male or female neonate with a brother weighs less, on average, than a neonate with a sister.…”

Section: Discussionmentioning

confidence: 99%

“…Birth weight is a primary indicator of fetal health known to be influenced by many factors (Beaty et al, 1997). A few population studies, in recent years, have explored the variations of the birth weight of the neonate with the reproductive antecedents of the mother, particularly its older siblings, with various results (Blanchard and Ellis, 2001; Cote et al, 2003; Magnus et al, 1985; Nielsen et al, 2008; Puts et al, 2006; Rahman, 2005; Rickard et al, 2007).…”

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confidence: 99%

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Influence of the mother's preceding pregnancies on fetal development and postnatal survival of the neonate, in normal pregnancy. An immunological phenomenon?

Vernier

Mackenzie

Schulzer

et al. 2010

American J Hum Biol

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Influence of the mother's preceding pregnancies on fetal development and postnatal survival of the neonate, in normal pregnancy. An immunological phenomenon?

Vernier

Mackenzie

Schulzer

et al. 2010

American J Hum Biol

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“…If a connection exists between the FBO effect and CGN, the large sexual orientation differences in CGN should make such a relationship readily apparent. Using a British sample, Rahman (2005) found no association between the FBO effect and psychological femininity in adulthood. The connection between FBO and CGN may even exist irrespective of sexual orientation.…”

mentioning

confidence: 75%

“…Likewise, Kishida and Rahman (2015) found no systematic association between CGN and the FBO effect in a large British sample of both androphilic and gynephilic males (i.e., those sexually aroused by and attracted to adult females). Using a British sample, Rahman (2005) found no association between the FBO effect and psychological femininity in adulthood.…”

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confidence: 75%

Birth order and recalled childhood gender nonconformity in Samoan men and fa'afafine

Semenyna

VanderLaan

Vasey

2017

Developmental Psychobiology

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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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“…This refers to the robust finding that homosexual men have more older brothers than heterosexual men, an effect ascribed to maternal immune responses triggered by carrying successive male fetuses which affects sexual differentiation of the brain of later born males (Bogaert et al, 2018). One study has reported no significant association between FBO and spatial cognition in heterosexual and homosexual males (Rahman, 2005b;cf. Bogaert, 2003acf.…”

Section: Discussionmentioning

confidence: 99%

Sexual Orientation and Cognitive Ability: A Multivariate Meta-Analytic Follow-Up

Norton

Rahman

2020

Arch Sex Behav

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A cross-sex shift model of human sexual orientation differences predicts that homosexual men should perform or score in the direction of heterosexual women, and homosexual women in the direction of heterosexual men, in behavioral domains such as cognition and personality. In order to test whether homosexual men and women's cognitive performance was closer to that of heterosexual men or that of heterosexual women (i.e., sex-atypical for their sex and closer to that of the opposite-sex), we conducted a multivariate meta-analysis based on data from our previous meta-analysis (Xu, Norton, & Rahman, 2017). A subset of this data was used and comprised 30 articles (and 2 unpublished datasets) and 244,434 participants. The multivariate meta-analysis revealed that homosexual men were sex-atypical in mental rotation (Hedges' g = −0.36) and the water level test (Hedges' g = −0.55). In mental rotation, homosexual men were in-between heterosexual men and women. There was no significant group difference on spatial location memory. Homosexual men were also sex-atypical on male-favoring spatialrelated tasks (Hedges' g = −0.54), and female-favoring spatial-related tasks (Hedges' g = 0.38). Homosexual women tended to be sex-typical (similar to heterosexual women). There were no significant group differences on male-favoring "other" tasks or female-favoring verbal-related tasks. Heterosexual men and women differed significantly on female-favoring "other" tasks. These results support the cross-sex shift hypothesis which predicts that homosexual men perform in the direction of heterosexual women in sex differentiated cognitive domains. However, the type of task and cognitive domain tested is critical.

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The association between the fraternal birth order effect in male homosexuality and other markers of human sexual orientation

Cited by 13 publications

References 19 publications

Influence of the mother's preceding pregnancies on fetal development and postnatal survival of the neonate, in normal pregnancy. An immunological phenomenon?

Influence of the mother's preceding pregnancies on fetal development and postnatal survival of the neonate, in normal pregnancy. An immunological phenomenon?

Birth order and recalled childhood gender nonconformity in Samoan men and fa'afafine

Sexual Orientation and Cognitive Ability: A Multivariate Meta-Analytic Follow-Up

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