Quantitative and genetic features of epidermal ridge minutiae on the palm of twins

The total minutia count (TMC) and fork index (FI), i.e., the proportion of forks in total minutiae, were examined in palm prints of 20 pairs each of monozygotic and dizygotic Japanese twins. No bilateral difference was found in either trait. The mean of the TMC was higher in males than in females, but the FI showed no sex difference. Both traits presented relatively high intraclass correlation coefficients between monozygotic twins, and genetic control of these traits is suggested. However, no correlation was observed between these two traits. A slight correlation was observed between the TMC and the total palmar interdigital ridge count. Some methodological problems concerned with classification criteria were discussed.