Proceedings: Genetic and environmental interaction in variation of skinfold thickness in children.

Abstract

The complexity of determining the relative importance of genetic and environmental influences in the variations observed in body build is considerable. The availability of triceps and subscapular skinfold measurements collected on identical and fraternal twins during childhood, together with suitable standard measurements, has provided an opportunity to do this. The proportion of variance for a characteristic which is due to genetic variation can be calculated from the difference between correlation coefficients of the characteristic observed in monozygotic and dizygotic twins, if it is assumed that the within-pair differences due to environmental factors would be similar for both. Triceps and subscapular skinfold thickness have been measured on 78 pairs of identical twins (38 male, 40 female), on 144 pairs of fraternal twins (67 male, 77 female), and on 117 pairs of fraternal twins of unlike sex. There were marked differences between the two sexes and between the two sites: age also considerably affected the results. In children under the age of 10 years environmental influences accounted for a large proportion of the variation of limb fat in both sexes and body fat in girls. In older children genetic factors accounted for a very large proportion of the variation in both types of fat in both sexes.