Genetic Longevity Explains Why Some People Live Much Longer

Published: 30 January 2026. The English Chronicle Desk. The English Chronicle Online.

The question of why some people live far longer than others has fascinated humanity for centuries. Many centenarians credit modest habits, calm lives, or even a nightly glass of whisky. New research now suggests that the answer may lie deeper within us. Scientists increasingly believe that genetic longevity plays a far greater role in determining lifespan than previously understood.

According to findings published in the journal Science, researchers argue that the influence of genes on how long humans live has been underestimated for decades. Earlier studies attempted to measure the genetic contribution to lifespan but failed to account for deaths caused by external events. Accidents, infectious diseases, violence, and environmental hazards often shorten lives for reasons unrelated to biological ageing. This oversight, scientists say, masked the true power of genetic longevity.

The research was led by Professor Uri Alon and his team at the Weizmann Institute of Science in Israel. Their work focused on the concept of heritability, which measures how much variation in a trait within a population can be explained by genetics rather than environment. Traits like height and weight have well-established heritability estimates. Lifespan, however, has remained elusive, with previous estimates ranging widely from six percent to thirty-three percent.

Professor Alon and his colleagues believe those figures are misleadingly low. They argue that external causes of death rise with age as people become more vulnerable. When these factors are not separated from biological ageing, the genetic signal becomes diluted. To address this, the team developed a mathematical model designed to filter out what they call extrinsic mortality, allowing the genetic component to emerge more clearly.

The model was calibrated using historical data from thousands of twin pairs in Denmark and Sweden. Twin studies are especially valuable in genetics because they allow researchers to compare individuals who share most or all of their DNA. By removing the effects of external mortality, the researchers found that genetics accounted for roughly fifty percent of the variation in human lifespan. This finding places humans alongside other mammals, such as laboratory mice, in terms of genetic influence on ageing.

The remaining fifty percent of lifespan variation was attributed to non-genetic factors. These include random biological processes and environmental influences experienced throughout life. Lifestyle choices, diet, physical activity, social connections, and living conditions all play significant roles. However, the study suggests that these factors operate alongside a strong genetic framework rather than independently of it.

Ben Shenhar, a co-author of the study, explained that everyday observation supports the findings. A notable proportion of centenarians reach extreme old age without suffering major chronic illnesses. This resilience, he suggested, may be explained by protective genetic traits. Over recent decades, scientists have already identified several genes associated with disease resistance and slower biological ageing. The new findings imply that many more such genes likely remain undiscovered.

The researchers tested their model using data from a United States study involving siblings of centenarians. The results were strikingly consistent, again showing that about half of lifespan variation could be explained by genetics. Further analysis of Swedish population data revealed another important trend. As public health improved during the twentieth century and deaths from infectious disease declined, the apparent genetic contribution to lifespan increased. This pattern supports the idea that when extrinsic mortality falls, genetic longevity becomes more visible.

The study also found that heritability varied depending on cause of death and age. Genetic influence appeared stronger in deaths linked to internal biological processes, such as dementia, than in those caused by cancer or external factors. This complexity highlights how genes interact with different diseases and ageing pathways across the lifespan.

Professor Alon hopes the findings will inspire renewed efforts to identify the genes responsible for regulating human ageing. Understanding these mechanisms could eventually lead to therapies that slow the ageing process itself. Rather than treating individual diseases, such interventions might reduce the risk of many age-related conditions simultaneously. This prospect represents a major shift in how medicine could approach ageing populations.

Not all scientists involved in ageing research were surprised by the conclusions. Professor Richard Faragher from the University of Brighton welcomed the study, noting that humans appear similar to other species commonly used in ageing research. This similarity increases confidence that treatments developed in animal models could translate effectively to humans. While caution remains essential, the findings strengthen the bridge between laboratory research and clinical application.

Despite the excitement surrounding the results, researchers stress that genes are not destiny. Even with a strong genetic predisposition for long life, environmental factors still matter. Healthy behaviours may not override genetics entirely, but they can influence how genetic potential is expressed. As people age, the balance between inherited traits and lived experience becomes increasingly complex.

The study does not fully address how genes interact with the immune system, an area that remains critical in determining vulnerability to disease. Future research is expected to explore this relationship in greater detail. Scientists are also keen to investigate how social inequality and environmental stressors may alter genetic expression over time.

What emerges from this research is a more nuanced understanding of ageing. Longevity is neither purely a matter of luck nor solely the result of good habits. Instead, it reflects an intricate interplay between genetic inheritance and life circumstances. The renewed focus on genetic longevity reframes the debate, offering fresh insight into why some individuals enjoy remarkably long and healthy lives.

As populations age across the world, these findings carry significant implications for healthcare planning and public policy. By understanding the biological foundations of long life, societies may be better equipped to support ageing citizens. While the promise of gene-based therapies remains distant, the path toward them is now clearer than ever.

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