Longevity Is Inherited

(Posted on Friday, February 13, 2026)

New research suggests that your genes may explain about half of your potential lifespan, a dramatic increase from previous estimates. Earlier twin and family studies typically estimated the heritability of human lifespan at 15%-33%. More recent analyses have lowered that figure to 6–16%. Those findings tell us: genes matter, but environment—diet, exercise, education, income, medical care and pure chance—dominate how long we live.

The new analysis in Science turns that view on its head, suggesting that once deaths from accidents, infections and other external hazards are stripped away, inherited biology may explain roughly half of the variation in human lifespan.

A New Concept

Older research on longevity treated all deaths equally. It didn’t separate deaths from things like accidents, war or infections from deaths caused by diseases like cancer or heart disease. However, these types of deaths happen for very different reasons. Some are due to outside factors, while others are more about our biology. The new study addresses this by separating deaths into two main types.

“Extrinsic” mortality means deaths from outside factors, like accidents, infections or natural disasters. “Intrinsic” mortality means deaths caused by aging or diseases that develop inside the body, like cancer or heart disease. In the past, many people died young from infections or poor healthcare, so it was harder to see how much genes affected lifespan.

More than 100 years of data from Scandinavian twins were analysed. Statistical models were used to note how death rates change as people get older, and to remove the effect of extrinsic deaths from accidents or infections. When looking only at deaths from aging and disease, it was found that genes explained about half of the differences in how long people lived after age 15. Therefore, genes play a much bigger role in how long someone lives than previously thought.

Public Health Evidence and What We See In People

These findings are supported by strong evidence. The model also predicted that siblings of Americans who live to 100 are themselves more likely to live long lives. Similarly, Swedish twins born in later decades, when mortality from accidents and infections was lower, showed a clearer genetic association with lifespan. In other words, external factors can mask the extent to which our genes influence longevity.

Yet while genes play a bigger role once external risks are reduced, the power of public health interventions remains clear. Improvements such as vaccines, antibiotics, better sanitation, safer roads and cardiovascular care have helped people live longer by reducing the impact of external dangers. That’s why, in the past, studies found low heritability for lifespan.

Survival was shaped more by exposure to infection, trauma and limited medical care than by inherited biology. The new research doesn’t downplay the value of these advances. Instead, it shows that as societies become safer and healthier, the influence of our genes on lifespan becomes more apparent and increasingly important for health planning.

Implications for Medical Innovation

If genes account for about half of our lifespan, this insight could transform how we develop medicines and plan for healthy aging. Treatments and drugs tailored to a person’s unique genetic profile may prove more effective than one-size-fits-all approaches. Large, long-term studies that follow people’s genes and health as they age will help discover which therapies work best for different groups and even individuals.

Saying that genes explain about 50–55% of lifespan does not mean your life is set in stone or that healthy habits don’t matter. Genes give you a tendency to live longer, but your choices and environment are still very important. Viewing lifespan this way helps us move beyond simplistic narratives that only blame or praise individuals for how they age. It also opens up more thoughtful discussions about fairness, healthcare access and what we can truly control. For physicians, this means that family history and genetics matter when discussing aging and risk, but encouraging healthy habits remains equally important.

Our genes and our environment shape how long we live. As science advances, we’ll be able to integrate what we know about genetics with evidence-based approaches to health, leading to more tailored advice and treatments. Ultimately, the best path to a longer life will likely blend personalized medicine with healthy choices for everyone.