• Posted February 2, 2026

Study Finds Genetics May Shape Up to 55% of How Long You Live

People are often told that eating well, exercising and avoiding bad habits are the fundamentals to a long life. 

But new research suggests something else may matter even more: genetics.

A large study published Jan. 29 in the journal Science suggests genetics could account for as much as 55% of a person’s lifespan. That’s far higher than earlier estimates, which ranged from 6% to 33%.

Researchers reached this conclusion by studying twins and separating deaths caused by external factors like accidents or infections, from deaths tied to internal aging, such as chronic disease or natural health decline.

By doing this, they said they were able to get a clearer picture of the relationship between genetics and longevity.

“The number that we got is not out of nowhere,” lead author Ben Shenhar, who studies aging at the Weizmann Institute of Science in Israel, told NBC News. “If you look at twin studies on pretty much anything in humans, you get this 50%. If you look at the heritability of age of onset at menopause, which is an age-related decline, that is also around 50%.”

Another expert, Morten Scheibye-Knudsen of the University of Copenhagen, said this approach helped remove what he called “outside noise” to better understand aging.

“We live [a maximum of] 120 years, and a yeast cell lives 13 days, and bowhead whales live 200 years,” Scheibye-Knudsen told NBC News. “So we already know our genes have set a limit to our lifespan, as it is now. I think people should have thought a little bit more about that because it cannot only be our behavior.”

But Dr. Eric Verdin, CEO of the Buck Institute for Research on Aging in California, said some deaths counted as “external” (such as those from infections like COVID) may still be influenced by genetics.

“We know that your genes play an enormous role in how you respond to infection,” Verdin explained.

Even so, Shenhar said his team rechecked the data while accounting for rising health risks with age, and genetics still explained about 50% of life expectancy.

The study also supports earlier research showing that people who live to 100 often have genes that lower their risk of chronic disease.

“It’s clear that these people are not just clawing their way to 100,” Shenhar added. “No, they have protective genes that protect against the harms of age.”

So far, only a few genes — FOXO3, APOE and SIRT6 — have been linked to longevity. Verdin said lifespan is likely dictated by many genes working together, not just one.

Still, both researchers stressed that lifestyle is critical.

If genetics explains 55%, that leaves 45% affected by things like diet, exercise and habits, Shenhar explained.

“The depressing thing about this is that it makes people be fatalistic,” Verdin added. “‘It doesn’t matter what I do. Why should I try to live better and not drink and do sport if it’s determined by genes basically?’ ”

But Shenhar pushed back.

“The message of our paper is not that lifestyle, exercise and diet are not important,” he said. “That is not our message, not at all. Even if your genetics gives you a particular potential or range for what your natural lifespan would be, depending on lifestyle, that might shift slightly one way or another. So it’s still important.”

More information

Harvard Health has more on longevity.

SOURCE: NBC News, Jan. 29, 2026