Dermatoglyphic asymmetry and sexual orientation in men

Dermal ridges on the fingertips are formed early in fetal life and remain unchanged throughout the life span. The researchers examined dermatoglyphic characteristics (total ridge count and directional ridge asymmetry) in homosexual and heterosexual men. There was no difference between the 2 groups of men in total ridge count, but more gay men demonstrated leftward asymmetry than did nongay men. Although this effect was not accounted for by differences in hand preference, an association was observed between leftward dermatoglyphic asymmetry and an increased incidence of adextrality in homosexual men, but not in heterosexual men. These findings are consistent with a biological contribution to sexual orientation and indicate that such an influence may occur early in prenatal life.