Genetics of dermal ridges: familial correlations for (<i>S/√10</i>), a measurement of the diversity of ridge‐counts from finger to finger

SummaryA value S2, the sum of squares of deviations of the ten separate finger ridge‐counts from their mean, has been used as a measure of the diversity between the digits of an individual.Familial correlations have been estimated using a diversity index, the function (S/√10), which is more symmetrically distributed than S2 in a population sample (though the distribution is not Gaussian).Parent‐child, sib‐pair and dizygotic twin‐pair correlations are approximately 1/4, while the monozygotic twin correlation coefficient is 0–73 ± 0–06.It is concluded that the diversity of the ridge‐count from finger to finger has a genetic basis, but environmental influences during early pre‐natal development have a considerable effect. S2 values for parents, children, additional sibs and twins are given in the Appendix.The data used for this paper are filed in the Archives at the Galton Laboratory.