When External Deaths Decline, Genes Take a Bigger Share of Lifespan

A twin-based study shows that removing deaths from accidents and infections raises the estimated genetic contribution to lifespan from about 20–25% to roughly 50–55%. This higher heritability reflects context and population, not stronger genes: as external threats decline, environmental and lifestyle factors still shape outcomes, and half of lifespan variation remains due to environment. The finding emphasizes that genes and environment interact, and aging genetics requires considering different contexts.