Family resemblance for fasting blood glucose: the Jerusalem Lipid Research Clinic.

Familial aggregation of fasting plasma glucose was studied in a sample of families examined at the Jerusalem Lipid Research Clinic. We first examined homogeneity of familial correlations across major origin groups in the Israeli sample. Correlations were generally homogeneous across origin groups, except for mother-son pairs. The pooled familial correlations were relatively low for unadjusted blood glucose values, and somewhat higher upon adjustment for sex, age, ethnicity, education, seasonality, body mass, cigarette smoking, alcohol consumption and dietary intake. Genetic and cultural determinants of blood glucose were estimated utilizing a path model with 10 parameters to be estimated from a total of 16 correlations. Under a reduced model genetic heritability (h2) was estimated to be 0.18 +/- 0.08 and cultural heritability (c2) was 0.10 +/- 0.02. However, within this population the additive variation could be explained by a cultural model of inheritance without introducing genetic parameters, and most of the variance is due to "random" unmeasured environmental factors. Commingling analysis was also performed, and our findings imply that there is no evidence for admixture in the distribution of fasting blood glucose in this Israeli population sample.