Familial aggregation of blood pressure and weight in adoptive families. III. Analysis of the role of shared genes and shared household environment in explaining family resemblance for height, weight and selected weight/height indices.

This study presents an analysis of the role of genetic and household environment in explaining the familial aggregation of height (HT), weight (WT), and body mass indices (WT/HT1.2 and WT/HT2.0). The biologic model used for the analysis partitions the covariances between family members into the contributions of genetic and environmental variability shared within and across generations, including a variance component shared only by a mother and her natural children. Tests of hypotheses suggest that shared genes and shared household environmental factors make significant contributions to the familial aggregation of WT (adjusted for age and sex) and of HT (adjusted for age and sex), whereas family resemblance of WT adjusted for age and HT can be attributed mostly to the effects of shared genes. The familial aggregation of selected WT/HT indices is attributed to the effects of shared household environment only, suggesting that these variables measure a characteristic of stature that is independent of height and weight.