A new study conducted by researchers at the Weizmann Institute of Science has significantly revised the understanding of factors influencing human lifespan. Traditionally, scientists believed that genetics played a minor role, estimating its contribution to lifespan differences at only 20-25% or even less. However, this new research indicates that genetics may actually account for about 50% of lifespan variation. The study, led by Ben Shenhar under the guidance of Prof. Uri Alon, analyzed extensive twin datasets from Sweden and Denmark, including twins raised apart, to isolate genetic factors from environmental influences. Earlier estimates were skewed by extrinsic mortality factors, such as accidents and infections, which were not adequately accounted for in previous studies. By employing innovative simulations to filter out these external causes of death, the researchers uncovered a stronger genetic influence than previously recognized. The implications of this research are profound, potentially reshaping aging studies and encouraging the identification of specific genes that could extend lifespan and inform therapeutic strategies. The study has been published in the journal Science, highlighting a significant shift in the understanding of human longevity.