title: Excess of counterclockwise scalp hair-whorl rotation in homosexual men.
abstract: While most men prefer women as their sexual partners, some are bisexual and others are homosexuals. It has been debated for a long time whether a person's sexual preference is innate, learned, or due to a combination of both causes. It was recently discovered that the human right-versus-left-hand use preference and the direction of scalp hair-whorl rotation develop from a common genetic mechanism. Such a mechanism controls functional specialization of brain hemispheres. Whether the same mechanism specifying mental makeup influences sexual preference was determined here by comparing hair-whorl rotation in groups enriched with homosexual men with that in males at large. Only a minority of 8.2% (n = 207) unselected 'control' group of males had counterclockwise rotation. In contrast, all three samples enriched with homosexual men exhibited highly significant (P < 0.0001), 3.6-fold excess (29.8%, n = 272) counterclockwise rotation. These results suggest that sexual preference may be influenced in a significant proportion of homosexual men by a biological/genetic factor that also controls direction of hair-whorl rotation.
authors.affiliation: amar.klar@gmail.com
authors.forename: Amar J S
authors.initials: AJ
authors.lastname: Klar
mesh_terms: D006197:Hair / Q000502:physiology*; D018451:Homosexuality, Male / Q000235:genetics*; D006801:Humans; D008297:Male; D018401:Sample Size; D012535:Scalp / Q000502:physiology*