Genetics Plays Larger Role in Lifespan Than Previously Believed, Weizmann Institute Study Shows

Researchers at the Weizmann Institute of Science in Israel published a study in April 2026 showing that genetics accounts for about 50-55% of human lifespan variation, more than double previous estimates. According to lead researcher Ben Shenhar, the study analyzed twin data from Sweden and Denmark and accounted for external mortality factors, which earlier studies had not separated from biological aging.

The study, published in the journal *Science* in April 2026, analyzed extensive twin data from Sweden and Denmark, including for the first time twins raised apart, to more accurately separate genetic influences from environmental and external mortality factors, according to lead researcher Ben Shenhar of the Weizmann Institute of Science in Israel. Shenhar said the research employed mathematical modeling to distinguish deaths caused by biological aging from those due to external causes such as infections, accidents, and unsafe working conditions, which had confounded previous estimates.

By neutralizing external mortality causes in the twin databases, the new analysis found that genetics accounts for approximately 50-55% of the variation in human lifespan, more than double prior estimates, Shenhar said.

Previous heritability estimates for human lifespan ranged from 6% to 25%, with many studies placing the genetic contribution at about 20-25%, according to Shenhar and co-authors. These earlier figures, the study noted, were skewed by high extrinsic mortality in past generations, which obscured the true genetic component.

The research team, based in the lab of Prof. Uri Alon at the Weizmann Institute, analyzed three large twin registries from Sweden and Denmark, drawing on decades of data. According to the study, this is the first lifespan heritability analysis to incorporate data from twins raised apart, providing a unique opportunity to isolate genetic effects from shared environmental factors. Shenhar stated, “For the first time, we neutralized external causes of death in existing databases,” allowing for a clearer assessment of intrinsic biological aging.

The study also examined the heritability of specific age-related diseases, finding that dementia shows a heritability of approximately 70% up to age 80, a figure substantially higher than that for cancer or heart disease, the researchers reported. This suggests a stronger genetic influence on certain conditions associated with aging. Shenhar said the findings enable researchers to link genetic differences to specific biological pathways regulating aging, which could inform future therapeutic strategies.

Experts outside the study underscored the significance of the findings. Daniela Bakula and Morten Scheibye-Knudsen from the University of Copenhagen described the results as having “important consequences for aging research,” according to a commentary in *Science*. The commentary also noted that the study’s robust methodology strengthens the rationale for large-scale efforts to identify gene variants associated with longevity.

The increased heritability estimate aligns closely with those of other complex human traits such as height, the study noted, and is consistent with lifespan heritability observed in animal models, lending further credibility to the findings. Shenhar emphasized that the breakthrough “corrected previous methodologies” and challenged the long-standing view that human lifespan was shaped almost entirely by non-genetic factors.

The research has implications for the development of therapies targeting aging itself rather than just individual age-related diseases, according to Shenhar and his team. The findings support refining polygenic risk scores for longevity prediction and open new avenues for identifying genetic markers that could inform personalized approaches to extending healthy lifespan.

The study represents a paradigm shift in understanding the genetic basis of human aging and longevity, according to the Weizmann Institute researchers. By accounting for extrinsic mortality factors and leveraging comprehensive twin data, the research provides a more precise estimate of the genetic contribution to lifespan variation, laying the groundwork for future investigations into the biology of aging.