Finger-length ratios and sexual orientation

  title={Finger-length ratios and sexual orientation},
  author={Terrance J. Williams and Michelle E. Pepitone and Scott E. Christensen and Bradley M. Cooke and Andrew D Huberman and Nicholas J. Breedlove and Tessa J. Breedlove and Cynthia L. Jordan and Stephen M. Breedlove},
Animal models have indicated that androgenic steroids acting before birth might influence the sexual orientation of adult humans. Here we examine the androgen-sensitive pattern of finger lengths, and find evidence that homosexual women are exposed to more prenatal androgen than heterosexual women are; also, men with more than one older brother, who are more likely than first-born males to be homosexual in adulthood, are exposed to more prenatal androgen than eldest sons. Prenatal androgens may… 
Anthropometric analysis of homosexuals and heterosexuals: implications for early hormone exposure
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Fluctuating asymmetry, second to fourth finger length ratios and human sexual orientation
  • Q. Rahman
  • Medicine, Psychology
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Examining nine bilateral somatic traits in 120 healthy heterosexual and homosexual men and women found that sexual orientation did not relate to composite FA scores, which constrain the number of possible neurodevelopmental pathways responsible for sexual orientation in humans.
Prenatal Influences on Sexual Orientation: Digit Ratio (2D:4D) and Number of Older Siblings
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  • Psychology, Medicine
    Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior
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Prenatal androgen levels are suggested to influence sexual orientation in both sexes. The 2D:4D digit ratio has been found to associate with sexual orientation, but published findings have often been
Sexual orientation and the 2nd to 4th finger length ratio: evidence for organising effects of sex hormones or developmental instability?
The evidence may suggest that homosexual males and females have been exposed to non-disruptive, but elevated levels of androgens in utero, but these data also draw attention to difficulties in the interpretation of results when somatic features are employed as biological markers of prenatal hormonal influences.
Brain Development and Sexual Orientation
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Sexual Identity and Sexual Orientation
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It seems therefore that the prenatal endocrine environment has a significant influence on human sexual orientation but a large fraction of the variance in this behavioral characteristic remains unexplained to date.
Differences in Finger Length Ratios Between Self-Identified “Butch” and “Femme” Lesbians
It is concluded that increased early androgen exposure plays a role in only some cases of female homosexuality, and that the sexual orientation of “femme” lesbians is unlikely to have been influenced by early androgens.
Prenatal Influences on Human Sexual Orientation: Expectations versus Data
  • S. Breedlove
  • Psychology, Medicine
    Archives of sexual behavior
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The data indicate that human sexual orientation is sufficiently polarized that groups of lesbians show evidence of greater prenatal androgen exposure than groups of straight women, while groups of gay men have, on average, a greater proportion of brothers among their older siblings than do straight men.
Intrauterine Position Effects on Anogenital Distance and Digit Ratio in Male and Female Mice
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The Relation Between Sexual Orientation and Penile Size
On all five measures of penile length and circumference, homosexual men reported larger penises thandid heterosexual men, and Explanations for these differences are discussed.
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  • Psychology, Medicine
    Behavioral neuroscience
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Investigation of whether lesbians, like homosexual men, have a later birth order relative to heterosexual comparisons supports theories of gender-specific mechanisms in the development of sexual orientation in women and men.
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Homosexual male probands with monozygotic cotwins, dizygotic cotwins, or adoptive brothers were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking
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Investigation of pedigree and linkage analyses on 114 families of homosexual men found increased rates of same-sex orientation were found in the maternal uncles and male cousins of these subjects, but not in their fathers or paternal relatives, suggesting the possibility of sex-linked transmission in a portion of the population.
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The objectives of the study are to summarize much that is known about the variation of the human sex ratio at birth and relate these findings to a hypothesis designed to explain them, and to outline some of the research needed to test the hypothesis.
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The levels of plasma testosterone of 19 young male homosexuals (Kinsey group VI) were found to be significantly higher (p < .01 ) than those of 20 strictly heterosexual men matched for average age.
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It is shown that 2D:4D in right and left hands has a sexually dimorphic pattern and is probably established in utero, which raises the possibility that patterns of digit formation may relate to spermatogenesis and hormonal concentrations.
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  • Psychology, Medicine
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The CEOAEs of homosexual and bisexual females were found to be intermediate to those of heterosexual females and heterosexual males, which is a parsimonious explanation for the change in their sexual orientation.