title: Determinants of ridge counts in MZ twin kinships.
abstract: The inheritance of total ridge count (TRC) was studied in 967 individuals from the families of 111 pairs of MZ twins. The sample included data on 47 male half-sibships with 227 offspring and 64 female half-sibships with 306 offspring. The males in this sample had a mean ridge count of 135 +/- 2 and the females a mean ridge count of 124 +/- 2. The distribution of scores for females showed evidence for significant skewness. For this reason, prior to the analysis, the data were corrected for sex and adjusted to normality using a power transformation. Nested analyses of variance were performed on the ridge counts from male and female half-sibships separately to derive estimates of among, between, and within-variance components. These estimates were then used in a nonlinear least squares program to estimate genetic and environmental parameters and to determine the goodness of fit of various models. A model which included additive genetic and dominance effects could not be rejected (P = 0.67) but did not fit the data as well as a simple additive genetic-random environmental model (P = 0.81). The addition of maternal effects to the later model also provided a satisfactory fit (P = 0.68). However, there were no improvement in the goodness of fit over the simple model, and estimated magnitude of the maternal effect was not significantly different from zero.
mesh_terms: D000704:Analysis of Variance; D003878:Dermatoglyphics; D005260:Female; D005826:Genetics, Medical; D006801:Humans; D008297:Male; D008433:Mathematics; D008957:Models, Genetic; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins; D014430:Twins, Monozygotic