How long we will live could be written in the genes, beyond the lifestyle

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The researchers turned to Swedish twins born between 1900 and 1935, a period marked by wars, economic crises and a pandemic, but also by significant improvements in sanitation, access to clean water and healthcare. This context functioned as a “natural experiment,” since many external causes of death had decreased. To contrast the results, they were compared with data from Danish twins born between 1870 and 1900, a time when infectious diseases – such as cholera or diphtheria – caused high mortality at early ages.

The analysis focused on some typical causes of aging: cancer, cardiovascular diseases and dementia. The results suggest that cancer appears to be less influenced by geneticswhile dementia shows greater hereditary dependence.

One of the most striking conclusions of the study is that More than 50% of the differences in lifespan within a population could be explained by genesa proportion much higher than that estimated in previous research, which placed it around 25% or less.

As Alon explained, this difference is due to the fact that previous studies included people who died young from causes unrelated to aging, such as accidents or infections. By reducing this “statistical noise”, the weight of genetics becomes more evident, while the role of lifestyle seems smaller.

The study thus suggests that, when deaths from external causes are reduced, genetics take on a more determining role in how long we liveespecially in diseases associated with aging.

And the lifestyle?

Does this mean that adopting healthy habits is no longer important? Not necessarily. Alon estimates that a healthy lifestyle could add about five years to life expectancy, while the absence of these habits could subtract a similar figure. Thus, if genetic predisposition places life expectancy around 80 years, good habits could extend it to 85, or reduce it to 75 in the opposite scenario.

However, other experts urge caution. The New York Times collected the opinions of Bradley J. Willcoxdirector of geriatric research at the University of Hawaii, who called the study “provocative,” although he expressed reservations. In his opinion, drawing a sharp boundary between intrinsic and extrinsic causes of death is problematicsince many are located in a “gray zone” where biology and environment interact. For example, genes can influence the severity of an infection, complicating its classification.

In that same line, Thomas Perlsgeriatrician and director of the New England Centenarian Study at Boston University, stressed to the same American media that the weight of genetics does not invalidate the importance of lifestyle. As he explained, especially in people without exceptional genetic inheritance, maintaining healthy habits can make a considerable difference in the years of life.

Perls cited observational studies from Harvard that illustrate this gap: a 50-year-old woman with healthy habits could live to be 93, compared to 79 for another with a poor diet, sedentary lifestyle, smoking and excessive alcohol consumption. In men, the difference is similar: a healthy lifestyle could allow them to reach the age of 88, compared to 76 for those who do not adopt it. However, the specialist concluded that when it comes to reaching extreme ages –beyond 90 or even 100 years old– genetics become decisive.