Genetics may play a far greater role in determining how long people live than previously believed, according to new research published in the journal Science. Earlier studies estimated that genes account for between 6% and 33% of lifespan variation, but the latest findings suggest the figure could be as high as 55%.
The study was led by Ben Shenhar of the Weizmann Institute of Science in Israel, who said lifespan is influenced by a complex mix of factors. “Longevity is shaped by lifestyle, genetics and randomness,” he explained, pointing to genetically identical individuals who grow up in similar environments but still die at different ages.
Researchers aimed to better quantify how much variation in lifespan can be attributed to genetics alone. To do this, they re-examined historical data from human twin studies, identifying flaws in earlier analyses. Previous research focused only on age at death, without considering cause of death, which may have distorted results.
For example, if one twin lived to 90 and died of natural causes while the other died at 30 from an infectious disease or accident, the difference could be wrongly interpreted as genetic. The researchers adjusted their models to account for the fact that risks such as infections, falls and violence change with age. Even after these corrections, genetics still explained around half of lifespan differences.
Shenhar said the findings align with broader research. “In twin studies on many human traits, you often see this 50% figure,” he noted, adding that age-related milestones like menopause show similar heritability. He also pointed to centenarians, who often carry genes that protect against age-related damage.
However, experts not involved in the study urged caution. Eric Verdin, head of the Buck Institute for Research on Aging, warned against fatalism. While genes matter, he said, lifestyle choices still play a crucial role. Shenhar agreed, stressing the study does not diminish the importance of diet, exercise and healthy habits, which can still influence how genetic potential plays out.
