Fingerprint asymmetry in male and female transsexuals

The different number of fingerprint ridges on the left compared to the right hand originates in the first trimester of pregnancy and remains unchanged. Leftward asymmetry, that is more ridges on the left, is more common in females. Males have a higher total ridge count for both hands. We studied 270 male-to-female transsexuals and 54 female-to-male transsexuals, plus 220 male and female controls. Male controls had a higher ridge count than female controls. Male and female controls did not differ on directional asymmetry. On directional asymmetry, homosexual male transsexuals differed from control males. Homosexual male and female transsexuals combined differed from male and female controls combined. Heterosexual male and female transsexuals combined did not differ from controls. Male non-homosexual transsexuals showed greater dermatoglyphic fluctuating asymmetry than all other groups combined. The data show an association between dermatoglyphics and sexual orientation, not transsexualism per se and dermatoglyphics.