Dermatoglyphic asymmetry: Relation to sex, handedness and cognitive pattern

The number of ridges on the fingertips has a major genetic contribution, and is fixed by the fourth month of fetal life. Most people have a higher count on the right-hand side (R > ), approx. 20% have a higher left-hand side (L > ) count. The incidence of higher left count is greater in women and in homosexual men. Direction of dermatoglyphic asymmetry was not found to be related to handedness in heterosexual subjects, although it had been related to hand preference in homosexual men. Groups of subjects with higher-left or higher-right counts, were compared on cognitive tasks previously shown to be sensitive to other measures of body asymmetry. As predicted from previous research, both men and women with L > count were better at tasks on which women typically excel, while R > subjects were better at tasks on which men typically excel. In addition, unlike the previous body-asymmetry study, R > subjects achieved higher scores on sex-neutral reasoning tests. The data suggest that intellectual pattern is significantly influenced before birth.