Friday, January 11, 2008

Homosexuaity & blood group & hair & eye color   posted by Razib @ 1/11/2008 03:53:00 PM

Via Dienekes, Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation:
The present study sought to expand the limited evidence that sexual orientation is influenced by genetic factors. This was accomplished by seeking statistical differences between heterosexuals and homosexuals for four traits that are known to be genetically determined: eye color, natural hair color, blood type, and the Rhesus factor. Using a sample of over 7,000 U.S. and Canadian college students supplemented with additional homosexual subjects obtained through internet contacts, we found no significant differences between heterosexuals and homosexuals regarding eye color or hair color. In the case of blood type and the Rh factor, however, interesting patterns emerged. Heterosexual males and females exhibited statistically identical frequencies of the A blood type, while gay men exhibited a relatively low incidence and lesbians had a relatively high incidence (p < .05). In the case of the Rh factor, unusually high proportions of homosexuals of both sexes were Rh- when compared to heterosexuals (p < .06). The findings suggest that a connection may exist between sexual orientation and genes both on chromosome 9 (where blood type is determined) and on chromosome 1 (where the Rh factor is regulated).

What do you think? Seems more plausible that the likelihood of homosexual orientation is partly conditional upon the other genetic factors or physiological parameters; rather then there being a common causal root. If, as some argue, homosexuality is due to a relatively recent pathogen then its relationship to particular blood groups may simply be a coincidence of varied immune response of the different ABO & Rh antigens. I would be curious as to the blood group status of the mothers of gay men and women; perhaps it is simply due to physiological conflict (this might be related to sibling order). Like IQ it seems highly likely that there's a biological component to the variation, but color me skeptical of any locus of large effect.

(FYI, I'm blood group A & Rh+)

Related: Number of biological older brothers predicts male homosexuality, The biology of homosexuality, He She didn't give you gay, did she?, Pinker on the gay gene, Gavrilets' models of homosexuality, Gay sheep, forbidden science? and The gay gene & other considerations.

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