Both handedness and dermatoglyphic asymmetry reflect early, prenatal influences and both have been reported to be associated with male sexual orientation; handedness has been related to female sexual orientation as well. Neurohormonal and developmental perturbation are two competing hypothesis that attempt to explain these connections. We attempted to replicate these associations and to extend dermatoglyphic asymmetry findings to women. Dermatoglyphic directional asymmetry and fluctuating asymmetry were unrelated to sexual orientation. Homosexual women, but not homosexual men, had highly significant increases in non-right-handedness compared with same-sex heterosexual controls. Although this pattern of results does not allow resolution of the two competing models, it does lend additional support to a biological basis of sexual orientation.
Mustanski, B., Newcomb, M., & Garofalo R. (2002). Dermatoglyphics, handedness, sex, and sexual orientation. Archives of Sexual Behavior, 31(1), 113-22.
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This article provides a comprehensive review and critique of biological research on sexual orientation published over the last decade. We cover research investigating (a) the neurohormonal theory of sexual orientation (psychoneuroendocrinology, prenatal stress, cerebral asymmetry, neuroanatomy, otoacoustic emissions, anthropometrics), (b) genetic influences, (c) fraternal birth-order effects, and (d) a putative role for developmental instability. Despite inconsistent results across both studies and traits, some support for the neurohormonal theory is garnered, but mostly in men. Genetic research using family and twin methodologies has produced consistent evidence that genes influence sexual orientation, but molecular research has not yet produced compelling evidence for specific genes. Although it has been well established that older brothers increase the odds of homosexuality in men, the route by which this occurs has not been resolved. We conclude with an examination of the limitations of biological … Read More »