Cohabitation, activity level, and energy intake in parent-child resemblance for selected biological traits

Activity level and energy intake were estimated from 3-day records, including a weekend day, in parents and children from families of French descent. Subcutaneous fat from the summation of six skinfolds, fasting serum triglycerides, total and high-density lipoprotein cholesterol, and submaximal power output (PWC₁₅₀ ) derived from a cycle ergometer test also were determined in these subjects. Dependent variables were normalized through log₁₀ or squre-root transformation, and scores were adjusted by generation for the effects of age and gender. Correlations with residual scores were performed with pairs of natural parents and child (N ≧ 1057) and pairs of foster parent and adopted child (N ≧ 283). Coefficients were generally little affected by statistical control over current activity level and energy intake. Pairs of biological relatives were classified as either very similar (25% of pairs) or very dissimilar (25% of pairs) in terms of energy intake or activity level. Correlations revealed that similarity or discordance in energy intake or activity level had only a slight effect on parent-child resemblance. In addition, duration of cohabitation had little influence on parent-child covariation. It was concluded that parent-child resemblance in subcutaneous fat, work capacity, and blood lipids are not significantly affected by current patterns of energy intake, activity level, or duration of cohabitation.