Biological and environmental sources of familial aggregation of blood pressure: the Jerusalem Lipid Research Clinic

Genetic and cultural determinants of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were estimated using a path model on a sample of families examined in the Jerusalem Lipid Research Clinic. This model involves 10 parameters to be estimated from a total of 16 correlations (leaving ample degrees of freedom to test the goodness-of-fit). The general model fitted SBP (X2(6) = 6.95, p = 0.33) and DBP (X2(6) = 5.44, p = 0.49) very well. Both genetic (h2) and cultural (c2) components of inheritance were statistically significant for both blood pressure variables. Under the most parsimonious model, genetic heritabilities (h2) were estimated to be 0.20 and 0.28 for SBP and DBP respectively. Cultural heritability (c2) was 0.12 for SBP and 0.08 for DBP. A significant fraction of the estimate for cultural inheritance was due to a sibling environmental effect not mediated through their parents. Within this population genetic factors, common environmental factors and concomitant variables such as sex, age and origin explained about 40% of blood pressure variability. Most of the variance appears to be due to unmeasured environmental factors and errors of measurement.