FAMILIAL CORRELATIONS, COHABITATION EFFECTS, AND HERITABILITY FOR CARDIOVASCULAR RISK-FACTORS

Familial correlations in cardiovascular risk factors were investigated with use of data from a community based sample of 1319 nuclear famili es involving 4178 adult persons collected in the Busselton Population Health Surveys over the period 1966 to 1981. The risk factors consider ed were systolic blood pressure, diastolic blood pressure, body mass i ndex, triceps fatfold, and cholesterol. All risk factors showed positi ve familial correlations, with correlations generally being lower for spouses than for parent-offspring pairs or for siblings. Spouse correl ations showed little variation with age, suggesting that observed corr elations are primarily due to assortative mating and not to cohabitati on. The parent-offspring correlations tended to decline with age of (a dult) offspring; this observation suggests that the effect of a shared household environment during childhood and adolescence diminishes ove r time when living apart during adulthood. The sibling correlations de creased with age for blood pressure and serum cholesterol and increase d with age for body mass index and triceps fatfold. The estimated heri tabilities were 27% for systolic and diastolic blood pressure, 37% for serum cholesterol, 52% for body mass index, and 23% for triceps fatfo ld. These results confirm that substantial familial aggregation of car diovascular risk factors occurs and that much of this aggregation has a genetic basis, although assortative mating (in spouses) and environm ental influences (in offspring and siblings) are also present. The nuc lear family should be considered as a point of intervention in cardiov ascular disease prevention programs.