A recent Science paper revisits the classic twin‑study estimate of lifespan heritability. Traditional analyses peg the figure between 23 % and 35 %, but the authors construct a mathematical simulator that strips away non‑aging deaths—accidents, disease, murder—to see how genetics alone shape longevity. Their model yields a heritability near 50 % in a controlled simulation environment to provide clearer insight.

The simulation introduces an extrinsic‑mortality parameter that aggregates all non‑genetic death causes. By gradually reducing this parameter, the model shows heritability climbing from the twin‑study baseline up to the 50 % plateau. The authors validate the simulator against Danish and Swedish twin cohorts, where observed estimates sit at 23 % and 35 % respectively in alignment with historical data.

Critics argue that the paper’s heavy reliance on a simplified mortality model risks overstating genetic influence. Supporters counter that by isolating age‑related factors, the study clarifies the true contribution of DNA to lifespan. The work also highlights how environmental interventions—reducing accident or disease risk—can shift the heritability curve, offering a new lens for public health.

Ultimately, the study reframes the debate over longevity genetics, suggesting that when non‑genetic noise is removed, life expectancy becomes a largely heritable trait. Researchers can now better estimate the genetic ceiling for lifespan and evaluate how policy or medical advances might alter that ceiling globally.