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Commentary on Kishida and Rahman (2015), Including a Meta-analysis of Relevant Studies on Fraternal Birth Order and Sexual Orientation in Men

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Notes

  1. Tangentially, this result is consistent with at least one large-scale study finding that homosexual men have smaller average family sizes than do heterosexual men (Blanchard, 2012). It is inconsistent with the balancing selection hypothesis that genes predisposing men to homosexuality escape elimination from the population because the decreased fertility of men with the heritable form of homosexuality is offset by an increased fertility among biological relatives who carry the same genetic variants.

  2. In these studies, same-biological-sex sexual orientation was determined via questionnaires for adolescents in the study by VanderLaan et al. (2014) and otherwise inferred based on childhood-onset of gender dysphoria.

  3. One group of original authors reported that the comparison of older sisters was not statistically significant, but they included no additional information, not even which of the observed means was higher.

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Authors and Affiliations

  1. Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada

    Ray Blanchard

  2. Gender Identity Clinic, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, ON, Canada

    Doug P. VanderLaan

Authors
  1. Ray Blanchard
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  2. Doug P. VanderLaan
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Correspondence to Ray Blanchard.

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Blanchard, R., VanderLaan, D.P. Commentary on Kishida and Rahman (2015), Including a Meta-analysis of Relevant Studies on Fraternal Birth Order and Sexual Orientation in Men. Arch Sex Behav 44, 1503–1509 (2015). https://doi.org/10.1007/s10508-015-0555-8

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  • DOI: https://doi.org/10.1007/s10508-015-0555-8

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