Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years

  title={Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years},
  author={R. Blanchard},
  journal={Archives of Sexual Behavior},
  • R. Blanchard
  • Published 2018
  • Psychology, Medicine
  • Archives of Sexual Behavior
  • 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… CONTINUE READING
    93 Citations
    Reassessing the Effect of Older Sisters on Sexual Orientation in Men.
    Homosexual Sons and the Fraternal Birth Order Effect: The Role of Elevated Maternal Intrauterine Testosterone
    • 4
    • Highly Influenced
    Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
    • S. Nila, P. Crochet, +4 authors M. Raymond
    • Psychology, Medicine
    • Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior
    • 2019
    • 5
    • Highly Influenced


    Fraternal Birth Order and Ratio of Heterosexual/Homosexual Feelings in Women and Men
    • 17
    Birth order and ratio of brothers to sisters in transsexuals.
    • R. Green
    • Psychology, Medicine
    • Psychological medicine
    • 2000
    • 92
    Quantitative and theoretical analyses of the relation between older brothers and homosexuality in men.
    • R. Blanchard
    • Psychology, Medicine
    • Journal of theoretical biology
    • 2004
    • 159
    Proportion of homosexual men who owe their sexual orientation to fraternal birth order: An estimate based on two national probability samples
    • R. Blanchard, A. F. Bogaert
    • Psychology, Medicine
    • American journal of human biology : the official journal of the Human Biology Council
    • 2004
    • 54
    Sibship Size, Sibling Sex Ratio, Birth Order, and Parental Age in Homosexual and Nonhomosexual Gender Dysphorics
    • 93
    Homosexuality in men and number of older brothers.
    • 224
    • PDF
    Birth Order and Sibling Sex Ratio of Children and Adolescents Referred to a Gender Identity Service
    • 60
    • PDF
    Birth Order and Sibling Sex Ratio in a Population with High Fertility: Are Turkish Male to Female Transsexuals Different?
    • 15