A family study of dermatoglyphic traits in India: Resolution of genetic and uterine environmental effects for palmar pattern ridge counts

The inheritance of palmar pattern ridge counts for individual palmar areas, combined distal areas, and all ten areas combined was investigated in families belonging to two strictly endogamous Brahmin castes of peninsular India. Ridge count phenotypes were obtained by the method proposed by Malhotra et al. (1981a), however, zero observations (indicating patterns not circumscribed by triradii) were excluded from analysis. Path analytic methods were applied in order to determine the relative influences of polygenes, intrauterine environment, and residual environment. The proportion of genetic variation was, in general, consistently greater in one population than the other, and significant intrauterine environmental effects were detected for the population with lower heritabilities. The results of this investigation suggest that a simple polygenic model may not be sufficient to explain the inheritance of ridge counts in the interdigital IV configurational area. Distal pattern ridge counts do not appear to be influenced by more or less uterine environmental effects than all areas considered together. The proportion of genetic variation for the total palmar pattern ridge count was 52% in both populations.