How long we live can be affected by many things. Some scientists thought that only a small part of our lifespan comes from our genes. They guessed the number was around 10‑25 percent.
Researchers at the Weizmann Institute of Science have new data that changes this picture. Their work, published in Science, suggests that genetics may explain about half of the differences we see in how long people live.
Why Old Numbers Were Too Low
The scientists looked at three huge twin databases from Sweden and Denmark. For the first time, they also used data from twins who grew up apart. This helped them tell apart genetic effects from the influence of the environment.
Older studies mixed together deaths caused by accidents, infections, or other outside reasons with deaths caused by the natural aging process. This mix made the genetic signal look smaller.
To fix this, the team built a new math model. They also ran computer simulations of “virtual twins.” By removing the deaths that came from outside causes, a clearer genetic pattern emerged. The result matches what scientists have seen in other traits and in animal studies.
Up to age 80, the risk of dying from dementia shows a heritability of about 70 % – much higher than for cancer or heart disease.
What This Means for Aging Research
If genes are that important, researchers may focus more on finding the specific DNA pieces that affect how long we live.
"When heritability is high, it gives us a reason to look for gene variants that could lengthen life," Shenhar explained. "Understanding these genes could help us learn how aging works and maybe even treat it."
Funding and Support
The work was supported by several groups, including the Sagol Institute for Longevity Research, the Knell Family Institute for Artificial Intelligence, and the Rising Tide Foundation.