Interaction of fraternal birth order and handedness in the development of male homosexuality

@article{Blanchard2006InteractionOF,
  title={Interaction of fraternal birth order and handedness in the development of male homosexuality},
  author={Ray Blanchard and James M. Cantor and Anthony F Bogaert and S Marc Breedlove and Lee Ellis},
  journal={Hormones and Behavior},
  year={2006},
  volume={49},
  pages={405-414}
}
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… Expand
Sex Ratio of Older Siblings in Heterosexual and Homosexual, Right-Handed and Non-Right-Handed Men
  • R. Blanchard
  • Psychology, Medicine
  • Archives of sexual behavior
  • 2008
TLDR
It is suggested that both heterosexual and homosexual non-right-handers contribute to the older brothers × handedness ×-sexual orientation interaction. Expand
Review and theory of handedness, birth order, and homosexuality in men
TLDR
The maternal immune hypothesis might be extended or modified to account for the apparent interaction of older brothers and handedness, and two possibilities are considered: non- right-handed foetuses are insensitive to the presence of maternal anti-male antibodies, and mothers of non-right-handedfoetuses do not produce anti- male antibodies. Expand
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TLDR
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Sexual orientation, handedness, sex ratio and fetomaternal tolerance-rejection.
TLDR
A new explanation for sexual relationships, sexual orientation, handedness and sibling SR is proposed, where lesbian embryos could induce tolerance from mothers with anti-female factors, and non-right-handedness could induce maternal tolerance, or change the maternal compatibility of "gay" embryos. Expand
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TLDR
There was evidence for a relationship among handedness, sexual orientation, and CGN, and mediation analysis revealed that handedness was associated with sexual orientation directly and also indirectly through the mediating factor of CGN. Expand
Birth Order, Sibling Sex Ratio, Handedness, and Sexual Orientation of Male and Female Participants in a BBC Internet Research Project
TLDR
The results yielded some evidence confirming prior findings that non-right-handedness is associated with homosexuality in men and women, that older brothers increase the odds of homosexuals in men, and that the effect of older brothers on sexual orientation is limited to right-handed men. Expand
Fraternal Birth Order, Handedness, and Sexual Orientation in a Chinese Population
TLDR
The results showed that homosexual women are more likely to be non-right-handed than heterosexual women, regardless of how sexual orientation was defined, whereas bisexual women areMore likely to been non- right-handedthan heterosexual women whenSexual orientation was assessed via sexual attraction and sexual identity. Expand
Extreme right-handedness, older brothers, and sexual orientation in men.
TLDR
An elevated rate of extreme right-handedness was found in gay or bisexual men relative to heterosexual men, and it was demonstrated that older brothers moderate the relationship between handedness and sexual orientation. Expand
Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years
  • R. Blanchard
  • Psychology, Medicine
  • Archives of sexual behavior
  • 2018
TLDR
The fraternal birth order effect is the tendency for older brothers to increase the odds of homosexuality in later-born males and in homosexual subjects with masculine versus feminine gender identities is compared and evidence for the reliability of the effect was consistent. Expand
Interaction of birth order, handedness, and sexual orientation in the Kinsey interview data.
TLDR
The results demonstrated that handedness moderates the relationship between older brothers and sexual orientation, and suggest that biological explanations of men's sexual orientation are likely relevant across time, as the Kinsey data comprise an older cohort relative to modern samples. Expand
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