Familial aggregation of blood pressure (BP), both systolic (SBP) and diastolic (DBP), was examined inconsanguineous and nonconsanguineous families from southern India. Path analysis of BP suggests in breeding effects, with the genetic variance for SBP being lower in the sample that included in bred families. Specifically, genetic heritability for SBP was 38% in the nonconsanguineous sample but only 23% in the combined sample. Genetic heritability for DBP (30%) did not vary by sample, nor were sample differences in cultural heritability detected for either SBP (over 35%) or DBP (about 18%). These findings are remarkably similar to those in a French-Canadian population of Quebec; both reports found a considerably larger effect of the home environment on BP than previous studies.