Heritability estimation of 2D:4D finger ratio in a Chuvashian population-based sample

Objectives: The purpose of this study was to evaluate the familial correlations and heritability of 2D:4D ratio traits using a large population-based sample of ethnically homogeneous pedigrees from Chuvasha and Bashkortostan Autonomies of the Russian Federation. Methods: We calculated the familial correlations and performed a heritability analysis of 2D:4D ratio traits in a sample of 1541 subjects (803 men and 738 women, mean age 47.78 ± 16.89 years, range 18-90 years). Results: Familial correlations of 2D:4D ratio traits showed no significant correlation for spouses; however, parent-offspring (0.15-0.28, P <.001) and sibling correlations (0.13-0.38, P <.009) were found to be significant. Heritability (H ² ) of visual classification of 2D:4D ratio was 0.36 for the left and 0.28 for the right hand; finger ratio was 0.55 and 0.66, respectively; the ray ratio was 0.49 and 0.59, respectively, thus indicating the existence of a clear familial aggregation of 2D:4D ratio variation in the Chuvashian pedigrees, which cannot be explained only by common environmental effects. Discussion: Results of our study suggest familial aggregations of finger ratio variation (for all traits) in Chuvashian pedigrees. No evidence of assortative mating was found.