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Arch Sex Behav (2008) 37:145149 DOI 10.1007/s10508-007-9274-0
ORIGINAL PAPER: MINOT SPECIAL ISSUE
Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation
Lee Ellis Christopher Ficek Donald Burke Shyamal Das
Published online: 12 December 2007 Springer Science+Business Media, LLC 2007
Abstract The present study sought to expand the limited evidence that sexual orientation is inuenced 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 signicant 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 ndings 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).
Keywords Sexual orientation Blood type Rhesus factor Hair color Eye color Genetics
Introduction
Several lines of evidence have pointed toward biological causes of variations in sexual orientation in recent years (Ellis, 1996; Ellis & Ames, 1987; Rahman, Kumari, & Wilson, 2003), although the specic nature of these causes remain unidentied. In the 1990s, a study tentatively pinpointed a region on the X-chromosome that might be responsible for variations in male sexual orientation (Hamer, Hu, Magnuson, Hu, & Pattattucci, 1993). Since this study was published, two additional studies have appeared bearing on the X-chromosome hypothesis regarding male homosexuality, one supportive (Hu et al., 1995) and the other non-supportive (Rice, Anderson, Risch, & Ebers, 1999). In the case of female sexual orientation, no research bearing on genetic etiology has yet been published.
The present study was undertaken to explore genetic inuences on sexual orientation...