Genetics May Determine Over Half of Lifespan, Study Finds

Lifestyle factors still play a crucial role in longevity, experts say.

Published on Feb. 8, 2026

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A new study published in the journal Science has found that genetics may account for up to 55% of a person's lifespan, more than double previous estimates. The researchers analyzed lifespan and genetics in twins across Denmark, Sweden, and the U.S. to make this discovery. However, experts stress that lifestyle factors like diet, exercise, and access to healthcare remain critically important, especially as people age.

Why it matters

This research provides new insights into the complex interplay between genetics and environmental factors in determining longevity. While the findings may seem discouraging for those hoping to prolong their lives through lifestyle choices, experts emphasize that healthy behaviors can still have a significant impact, especially in buffering against genetic vulnerabilities as people get older.

The details

The study used data from twin registries to separate the influence of genetics from external factors like accidents or disease. Researchers found that deaths caused by internal factors like aging or genetics rise more quickly with age compared to deaths from external causes. They calculated that genes may determine up to 55% of a person's lifespan. The rest is likely influenced by environmental factors and random genetic changes. The study suggests genetics play the biggest role in risk of death from conditions like dementia, followed by cardiovascular disease and cancer.

  • The study was published in the journal Science on February 8, 2026.

The players

Ben Shenhar

Lead study author and researcher on the physics of aging at the Weizmann Institute of Science in Rehovot, Israel.

Leonard E. Egede, M.D.

Chair of the Department of Medicine at the University at Buffalo, Jacobs School of Medicine and Biomedical Sciences.

Janet O'Mahony, M.D.

Internist at Mercy Medical Center in Baltimore, MD.

Leigh Frame, Ph.D.

Executive director of the Office of Integrative Medicine and Health at George Washington University.

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What they’re saying

“Lifespan is influenced by hundreds, if not thousands, of genes—not a select few.”

— Ben Shenhar, Lead study author and researcher on the physics of aging

“Genes do not operate in isolation. They set a range of possibilities rather than a fixed outcome, influencing how individuals respond to environmental exposures, lifestyle behaviors, and aging itself.”

— Leigh Frame, Ph.D., Executive director of the Office of Integrative Medicine and Health

“Poor lifestyle is still an important driver of morbidity and mortality. Healthy diet, moderate exercise, stress management, and not smoking are key lifestyle modifications that should still be encouraged.”

— Leonard E. Egede, M.D., Chair of the Department of Medicine

What’s next

Researchers say further study is needed to better understand the specific genetic pathways that enable some people to live longer, healthier lives. This could help guide future research into longevity drugs and interventions.

The takeaway

While genetics play a significant role in determining lifespan, accounting for up to 55% according to this study, lifestyle factors remain critically important, especially as people age. Healthy behaviors like diet, exercise, and regular medical care can help buffer against genetic vulnerabilities and support longevity.