Familial correlations of longevity: an isolate-based study.

Familial correlations for age at time of death have been computed in a French Canadian isolate. We show that parent-offspring correlations as well as sib correlations are of the same order of magnitude as that between spouses for various age groups at death. It is suggested that heritability of survival is nearly zero. Observed variability in survival is interpreted as the effect of environmental differences acting upon age-dependent genes.