According to a major international twin study published Thursday, the Human Lifespan Study finds that a person’s genes may account for up to 55% of how long they live, suggesting that genetics plays a far larger role in lifespan than previously believed.
The Human Lifespan Study, published in the journal Science, finds that genetic factors contribute more than half of a person’s potential lifespan, sharply revising earlier estimates that placed heritability at 6%–33%. Researchers say the findings reshape long-standing debates about aging, health, and longevity.
New Method Reveals Stronger Genetic Influence
The international research team analyzed decades of data from human twin studies, a common method for separating genetic and environmental influences. The researchers introduced a new analytical approach that distinguished between extrinsic and intrinsic causes of death.
Extrinsic mortality includes deaths caused by external forces such as accidents, homicides, environmental hazards, and infectious diseases. Intrinsic mortality refers to deaths driven by internal biological processes, including age-related diseases, genetic mutations, and the gradual decline associated with aging.
By separating the two, researchers explained that the Human Lifespan Study was able to more accurately isolate the influence of genetics on lifespan.
“The number that we got is not out of nowhere,” said lead author Ben Shenhar, a researcher who studies the physics of aging at the Weizmann Institute of Science. “If you look at twin studies on pretty much anything in humans, you get this 50%.”
Shenhar added that other age-related traits, including age of menopause onset, show similar levels of heritability, reinforcing the study’s conclusions.
Scientists Debate Boundaries Of Genetic Impact
Morten Scheibye-Knudsen, an associate professor at the University of Copenhagen who wrote an accompanying editorial, said the Human Lifespan Study introduces a method that helps remove confounding influences which have long obscured the biology of aging.
“We live a maximum of about 120 years, yeast cells live 13 days, and bowhead whales live 200 years,” he said. “The Human Lifespan Study shows that our genes have already set limits to lifespan, meaning it cannot only be our behavior.”
Not all experts are fully convinced that the genetic contribution is so clearly defined. Eric Verdin, president and chief executive of the Buck Institute for Research on Aging in California, said vulnerability to infections such as COVID or the flu may blur the line between extrinsic and intrinsic mortality.
“We know that your genes play an enormous role in how you respond to infection,” Verdin said. “So depending on how you classify that, the genetic contribution might be slightly lower.”
Shenhar said the team accounted for that concern by rerunning the analysis while adjusting for increased vulnerability to infections and falls with age. The results still showed genetics accounting for roughly half of life expectancy.
Longevity Genes Exist, But Lifestyle Still Matters
The findings may challenge the claims of longevity influencers and biohackers who promote supplements and personalized drug regimens as paths to dramatically extended life.
Researchers say the Human Lifespan Study supports the idea that long-lived individuals carry protective genes that reduce their risk of chronic disease. Previous research has linked longevity to variants of genes such as FOXO3, APOE, and SIRT6, though these variants are not present in all centenarians.
“The search has not been very fruitful,” Verdin said. “It suggests that longevity is driven by multiple genes interacting with each other, not a single genetic switch.”
Both Verdin and Shenhar cautioned that the Human Lifespan Study should not be seen as a reason to abandon healthy habits. If genetics accounts for 55% of lifespan, the remaining 45% is still influenced by behavior and environment.
“The message of our paper is not that lifestyle, exercise, and diet are not important,” Shenhar said. “Even within your genetic range, lifestyle can shift outcomes one way or another.”
Researchers say the next step is sequencing the genomes of more centenarians to better understand how combinations of genes contribute to long life.
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