Heritability of lifespan

Heritability of lifespan is the proportion of variance in age at death attributable to additive genetic differences among individuals in a defined population. Classic twin-study estimates placed narrow-sense heritability at roughly 20–30% (Herskind et al. 1996); large-scale genomic analyses and a 2018 study in Genetics (Ruby et al.) using genealogical databases suggested even lower heritability once marital assortment is properly accounted for, with some estimates falling below 10% for lifespan itself. More recent analyses (Shenhar et al. 2026, Science) that better account for confounding factors place the intrinsic heritability of human life span at approximately 50%, suggesting earlier estimates may have been deflated by failure to separate intrinsic from extrinsic mortality. Even at the higher end, modifiable factors — lifestyle, environment, stochastic events — account for a substantial portion of variance. Specific genetic variants such as APOE ε4 and FOXO3A show replicated associations with mortality risk and exceptional longevity respectively, even if their individual effect sizes are modest.