Evidence of sex-linked effects on the inheritance of human longevity: a population-based study in the Valserine valley (French Jura), 18-20th centuries.
A long-standing puzzle in gerontology is the sex dependence of human longevity and its inheritance. We have analysed the sex-linked pattern of inheritance of longevity from 643 nuclear families on the historical population register of a French valley. We have focused on mean conditional life expectancy at a minimum age of 50 years, thus, in the present study, longevity refers to late or post-reproductive survival. A comparison of parents' and offspring's longevity has shown the existence of a heritable component of late survival in this population. We have found that the heritable component was substantially larger for daughters compared to sons. Moreover, this result appeared to be specific to late survival, that is, when only post-reproductive mortality for parental and offspring generations is taken into account. The stronger resemblance of parents to their daughters was no longer observed when considering younger ages at death for the offspring. This observation explains the hitherto unaccountable diversity of data in previous studies.