Podcast Episode
For decades, the scientific consensus held that inherited genes accounted for just twenty to twenty-five percent of lifespan variation. The rest was attributed to environmental factors, lifestyle choices, and random chance.
The key innovation was distinguishing between "extrinsic" mortalityÔÇödeaths from external causes like accidents, violence, and infectious diseasesÔÇöand "intrinsic" mortality, which stems from the biological processes of ageing itself.
Previous studies failed to separate these factors, which the researchers argue masked the true genetic signal. When twins from previous centuries died young from tuberculosis or workplace accidents, it appeared that genetics played a smaller role than it actually does.
However, lifestyle still matters significantly. Uri Alon emphasises that healthy habits like exercise, diet, and social connection could shift a person's genetically influenced lifespan by about five years in either direction. Someone genetically predisposed to live eighty years could reach eighty-five with healthy choices, or drop to seventy-five with poor ones.
The findings could reinvigorate funding for genetic research into ageing, with researchers now having stronger justification to search for the specific gene variants that influence longevity.
Your DNA May Decide Half Your Lifespan, Not Just a Quarter
January 29, 2026
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A groundbreaking study published in Science reveals that genetics account for roughly fifty-five percent of human lifespan variation, more than doubling previous estimates of twenty to twenty-five percent. Researchers from the Weizmann Institute achieved this by mathematically filtering out external causes of death like accidents and infections from historical twin studies.
Genetics Plays a Much Bigger Role Than We Thought
A major new study is reshaping our understanding of what determines how long humans live. Research published in the journal Science suggests that approximately fifty-five percent of the variation in human lifespan comes down to geneticsÔÇömore than double what scientists previously believed.For decades, the scientific consensus held that inherited genes accounted for just twenty to twenty-five percent of lifespan variation. The rest was attributed to environmental factors, lifestyle choices, and random chance.
The Methodology Behind the Discovery
Researchers from the Weizmann Institute of Science in Israel, led by doctoral candidate Ben Shenhar and senior author Uri Alon, re-examined decades of twin studies from Denmark and Sweden, some dating back to the eighteen hundreds.The key innovation was distinguishing between "extrinsic" mortalityÔÇödeaths from external causes like accidents, violence, and infectious diseasesÔÇöand "intrinsic" mortality, which stems from the biological processes of ageing itself.
Previous studies failed to separate these factors, which the researchers argue masked the true genetic signal. When twins from previous centuries died young from tuberculosis or workplace accidents, it appeared that genetics played a smaller role than it actually does.
Why This Matters Now
The revised estimate brings human lifespan heritability in line with most other complex physiological traits, which typically show around fifty percent genetic determination. It also validates research efforts to identify longevity-associated genes.However, lifestyle still matters significantly. Uri Alon emphasises that healthy habits like exercise, diet, and social connection could shift a person's genetically influenced lifespan by about five years in either direction. Someone genetically predisposed to live eighty years could reach eighty-five with healthy choices, or drop to seventy-five with poor ones.
The findings could reinvigorate funding for genetic research into ageing, with researchers now having stronger justification to search for the specific gene variants that influence longevity.
Published January 29, 2026 at 9:31pm
