For years, the advice around living longer has been simple and repeated everywhere.
Eat better, exercise regularly, avoid smoking, manage stress, and you’ll give yourself the best chance at a long life—that was the general idea. Genetics were always mentioned, but usually treated as something that played a smaller, background role.
A new study from the Weizmann Institute of Science is now challenging that idea in a much bigger way than expected. Researchers suggest your genes may play a far larger role in how long you live than scientists previously believed. Instead of being a minor factor, genetics could account for roughly half of the differences in lifespan between people, which changes the conversation quite a bit.
For a long time, scientists believed lifestyle mattered more.
Earlier research generally estimated that genetics explained around 20 to 25% of lifespan differences, and some studies even suggested it could be less than 10%. That helped build a widely accepted belief that lifestyle and environment were doing most of the work. It makes sense given that people can clearly see the impact of habits like smoking, diet, and activity levels. As a result, it became easy to assume that those choices were the main drivers, while genetics simply added a small amount on top.
That thinking also gave people a strong sense of control. If lifestyle is the main factor, then changing how you live should have a direct and meaningful impact on how long you live. This study doesn’t completely undo that idea, but it does challenge how much control we actually have.
The new research has discovered something a bit different.
The new study, based on large-scale data analysis, found something quite different. After adjusting the way lifespan was measured, researchers concluded that genetics may account for around 50 percent of the variation in how long people live. That’s a major change from earlier estimates. It suggests your DNA could be playing a much stronger role behind the scenes, influencing how your body ages and how long it continues to function over time.
Obviously, this doesn’t mean lifestyle stops mattering, but it does suggest it may not be as dominant as previously believed. Instead, lifespan appears to be shaped by a more balanced mix of both genetics and environment.
A set of twins helped reveal the real picture.
To get clearer answers, researchers turned to one of the most reliable methods for studying genetics, twin data. Twins share the same DNA, which makes them ideal for comparing genetic influence against environmental factors.
What made this study more powerful is that it included twins who were raised apart. That allowed scientists to compare people with identical genetics but very different lifestyles, giving a much clearer view of what is inherited and what is influenced by surroundings.
By analysing these datasets, researchers could separate genetic influence more effectively than in previous studies. This helped uncover patterns that had been hidden when environment and genetics were too closely mixed together.
Why earlier studies may have missed this
One of the biggest issues with past research is how deaths were measured. Many studies grouped all causes of death together, including accidents, infections, and other unpredictable events. These are known as external causes, and they don’t reflect how the body ages naturally. If someone dies in an accident, it doesn’t tell you much about their lifespan in a biological sense. But these cases were still included in earlier data.
This study took a different approach by filtering out those external causes using new modelling techniques. Once those factors were removed, the genetic influence became much clearer, revealing a stronger link than previously recognised.
This can and should change how we think about ageing.
If genetics plays a larger role, it changes the idea that we can fully control our lifespan through lifestyle alone. It suggests there may be a natural range set by your biology that you operate within. That helps explain something people often notice in real life. Two people can live in similar ways, eat similar foods, and follow similar habits, yet age very differently. One might stay healthy into old age, while the other develops issues earlier.
This research suggests that difference may come down to genetics more than previously thought. Your body may already have certain tendencies that shape how it responds over time.
The takeaway is about balance, not control.
This doesn’t mean your life is fully predetermined, and it doesn’t mean healthy habits are pointless. Lifestyle still affects how your body functions, how you feel, and your overall quality of life. However, it does suggest that lifespan itself may be influenced more heavily by genetics than we realised. In simple terms, you can influence how well you age, but you may not have complete control over how long you live.
The most realistic way to look at it is as a balance. Your genes may set the boundaries, while your lifestyle affects where you fall within them. You don’t control everything, but you’re not powerless either.
