Genetic and environmental influences on growth of Philadelphia Black and White schoolchildren

Abstract

Sibling correlations in body size and composition are considered in 114 pairs of American Black and 101 pairs of White sibs, ranging in age from 6 to 12 years. Correlations were similar in the two races. Sibling resemblance was more or less similar for skeletal measurements (0.35-0.48), limb circumferences (0.41-0.43), and skinfolds (0.31-0.41). Age difference between members of a pair was found to affect the sibling correlations, especially for measurements of low genetic control. This is taken as evidence for environmental contributions to sibling resemblance. Higher sister-sister similarities in fat (as compared to brother-brother) were evident in Blacks (as they were in a rural South American sample) but not in Whites. This pattern could arise from similar sex-role differentiation in these two cultures (Afro and Latin American) or similar expression of sex-limited genes under less favourable environmental conditions.