Dermatoglyphic analysis of total finger ridge count in female monozygotic twins discordant for sexual orientation

L. Hall

This study was designed to test the hypothesis that prenatal environment contributes to the development of sexual orientation in females. The reseach involved a dermatoglyphic analysis of finger ridge count in two groups of female monozygotic twins: a study group which was discordant for sexual orientation, and a control group which was concordant for sexual orientation. In the female control group ridge counts were not significantly different. However, in the study group of female twins discordant for sexual orientation, the lesbian twins showed a consistent trend for lower total finger ridge counts than their heterosexual cotwins. It is concluded that in females, prenatal environmental difference are correlated with differences in sexual orientation, and that second trimester prenatal environment is likely to be a contributing factor in the etiology of this trait.