Familial correlations are available for individuals reared by biological and foster parents, with and without indices of relevant environment. Five data sets give estimates of genetic heritability which range from 0.194 to 0.360 for systolic pressure and from 0.147 to 0.346 for diastolic pressure. Concomitant estimates of cultural heritability due to common family environment range from 0.042 to 0.183 for systolic pressure and from 0.008 to 0.310 for diastolic pressure. There is good resolution of genetic and environmental determinants. Most of the variance is due to random environment and errors of measurement. Although estimates of variance components are spatiotemporally limited to particular populations, there is good agreement among data sets.