title: Gender Nonconformity and Birth Order in Relation to Anal Sex Role Among Gay Men.
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.
authors.affiliation: 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.
authors.forename: Ashlyn
authors.initials: A
authors.lastname: Swift-Gallant
authors.affiliation: 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.
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Coome
authors.affiliation: 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.
authors.forename: D Ashley
authors.initials: DA
authors.lastname: Monks
authors.affiliation: Department of Psychology, University of Toronto, 100 St. George St., Toronto, ON, M5S 3G3, Canada. doug.vanderlaan@utoronto.ca.|Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada. doug.vanderlaan@utoronto.ca.|Underserved Populations Research Program, Child, Youth and Family Division, Centre for Addiction and Mental Health, 1001 Queen St. W., Toronto, ON, M6J 1H4, Canada. doug.vanderlaan@utoronto.ca.
authors.forename: Doug P
authors.initials: DP
authors.lastname: VanderLaan
mesh_terms: D000328:Adult; D001722:Birth Order; D000068116:Gender Dysphoria; D005783:Gender Identity; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D012725:Sexual Behavior; D035781:Siblings; D011795:Surveys and Questionnaires
keywords: Anal sex role; Birth order; Gender nonconformity; Maternal immune hypothesis; Sexual orientation