Finger-length ratios show evidence of prenatal hormone-transfer between opposite-sex twins

@article{Anders2006FingerlengthRS,
  title={Finger-length ratios show evidence of prenatal hormone-transfer between opposite-sex twins},
  author={Sari M. van Anders and Philip A. Vernon and Christopher J. Wilbur},
  journal={Hormones and Behavior},
  year={2006},
  volume={49},
  pages={315-319}
}

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References

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Differences in 2D:4D ratio suggest that MZ twins share virtually the same genes, and lower ratio in lesbians is a result of differences in prenatal environment.
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The androgen-sensitive pattern of finger lengths is examined, and there is evidence that homosexual women are exposed to more prenatal androgen than heterosexual women are, and men with more than one older brother, who are more likely than first-born males to be homosexual in adulthood, are exposure to more pregnancies than eldest sons.
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