Genes or Lifestyle: Which Matters More for Longevity?

If longevity is written into your DNA, do your daily habits really matter?

For decades, scientists believed that lifestyle and environment did most of the heavy lifting when it came to determining a person’s lifespan. There is still consensus that modifiable factors like physical activity, diet, sleep, stress, and social connection play a major role in both lifespan and health span, or the number of years a person enjoys good health as they age.

However, research on longevity continues to evolve, with a new study suggesting genes may have a much bigger impact than previously thought.

Previous twin and family studies relied heavily on data from people born in the late nineteenth and early twentieth centuries, when deaths from causes unrelated to biological aging — things like infections, accidents, violence, and natural disasters — were 10 times more common than today, says first author of the new study, Ben Shenhar, a doctoral candidate and researcher at the Weizmann Institute of Science in Rehovot, Israel.

Those historical conditions created misleading signals, he says. “You would sometimes see twins where one died at age 30 and the other lived to 95. Today, that would be extremely unusual, but back then it wasn’t.”

To get a more accurate assessment, Shenhar and his colleagues developed a mathematical modeling approach designed to separate deaths caused by external events from deaths driven by biological aging.

When they applied that model, the picture changed substantially. The researchers estimate that inherited genetic factors account for roughly 50 percent to 55 percent of expected lifespan — about double earlier estimates.

“This study convincingly showed that earlier estimates of the genetic contribution to lifespan were too low,” say Charles Brenner, PhD, Alfred E. Mann Family Foundation Chair in the Department of Diabetes and Cancer Metabolism at the Beckman Research Institute of City of Hope in Duarte, California, and wasn’t involved in the research.

“Our findings do not suggest that lifestyle is not important for longevity, not at all. Even if 50 percent of lifespan is heritable, that still leaves another 50 percent,” says Shenhar.

For most people, longevity is shaped by many genes working together — each contributing modest effects that interact with lifestyle and environment over time.

But some people may win the “genetic lottery” by inheriting a small number of rare variants that may powerfully extend their lifespan.

Research into centenarians (people who live to 100 or older) shows that these variants don’t prevent aging itself. Instead, they appear to delay the onset of age-related diseases.

APOE2 Gene Variant One of the most consistently replicated longevity genes is APOE, which regulates cholesterol transport. “The APOE2 allele is significantly enriched in long-lived individuals and appears to offer neuroprotective and cardiovascular benefits,” says Shenhar.

FOXO3A Gene “Another key gene linked to exceptional longevity is FOXO3A, which regulates cellular stress responses, DNA repair, and insulin signaling,” says Shenhar. Variants in this gene have been found in “long-lived” populations around the world, likely because they help cells withstand stress that would otherwise lead to deterioration, Shenhar says. Additional studies are needed to confirm the impact of this gene on longevity and age-related illness.

CETP Gene CETP is linked to larger, healthier cholesterol particles, which helps protect against vascular aging, says Shenhar.

Some inherited conditions dramatically increase the risk of serious disease earlier in life, effectively lowering the baseline for longevity.

APOE4 Gene Variant Unlike the APOE2 variant that promotes longevity, the APOE4 variant is associated with increased risk of Alzheimer’s and heart disease, highlighting how different versions of the same gene can influence aging in opposite directions.

BRCA1 and BRCA2 Mutations in these genes impair the cell’s ability to repair DNA, raising the lifetime risk of aggressive breast and ovarian cancers, often at younger ages than average, says Shenhar.

Familial Hypercholesterolemia (FH) This inherited condition prevents the body from clearing LDL (“bad”) cholesterol efficiently, leading to dangerously high levels from birth, and heart attacks in people as young as their twenties or thirties if untreated.

Knowing your family history, which could offer clues about your genetic inheritance, can help guide conversations with your healthcare team about prevention and screening.

Brenner points to evidence-based screening tests that are already part of routine care, including mammograms for breast cancer and colonoscopies for colorectal cancer.

Similarly, colorectal cancer screening is typically recommended starting at age 45 for people at average risk. But those with a family history of colorectal cancer may need to begin earlier or be screened more frequently.

Even if genetics account for about half of aging-related lifespan, lifestyle still matters and may matter more the older you get, says Shenhar.

For example, it could take decades for unhealthy habits to translate into serious disease for someone in their thirties. But for someone in their eighties, the margin for error is smaller, and the impact can be more immediate.

One reason lifestyle matters is epigenetics, the system that controls how and when your genes are “read.” Daily habits can influence whether certain genes are “activated” and which ones stay “quiet,” explains David Rehkopf, PhD, a professor of epidemiology and population health at Stanford University in California.

An individual’s epigenetic profile reflects both genetic inheritance and environmental exposures. “It’s a mechanism through which genes and environment jointly influence health — but importantly, it’s changeable over the course of life,” says Dr. Rehkopf.

That means daily habits can influence how genetic risk plays out. “If someone has an unhealthy epigenetic profile now, changes they make can help it shift in a healthier direction over time,” he says.

No single habit determines longevity on its own. “All of the major lifestyle factors — diet, physical activity, sleep, and stress — play a role,” says Rehkopf. “It’s not about getting an A-plus in one category. It’s about balance, because they all matter for everyone.”

1. Exercise: Move More, Sit Less

Physical activity is one of the behaviors most consistently linked to living longer. Research suggests, for example, that just 10 extra minutes of exercise a day may lower the risk of early death by 15 to 35 percent.

But research using wearable devices suggests that sedentary time matters, too.

2. Nutrition: Eat More Plants

Diet appears to influence longevity largely by shaping the risk of chronic diseases that shorten life.

In a large modeling study, researchers concluded that if a 40-year-old eating the average American diet switched to a healthier diet and sustained those changes throughout their lifetime, they could potentially live nearly 10 years longer.

3. Sleep: Ensure the Brain Gets Its Nightly ‘Rinse Cycle’

Sleep appears to influence longevity primarily by shaping long-term health rather than acting as a standalone driver of lifespan. Adequate sleep allows the body and brain to process metabolic waste, recharge, and support the immune system, among numerous other functions.

4. Stress: Learn How to Manage Cortisol Levels

Chronic stress raises cortisol levels and is associated with inflammation, heart disease, and metabolic dysfunction. Experts believe that, over time, biological wear and tear may accelerate aging, including faster shortening of telomeres — the “protective caps” on DNA that help keep them stable.

Shorter telomeres are tied to higher risks of conditions like heart disease and metabolic disorders, making them one of several biological markers tied to how the body ages over time.

Research on long-lived populations in the world’s “Blue Zones” (including Sardinia in Italy and Okinawa in Japan) suggest that longevity isn’t just shaped by habits like diet or exercise, but by daily social connection. People in these communities tend to eat together, spend more time with family and friends, and remain socially engaged well into older age.

Strong social ties have been linked to lower risks of heart disease, cognitive decline, and premature death, while chronic loneliness has been associated with higher mortality risk comparable to other major health threats.

Lifestyle choices don’t happen in a laboratory. Air quality, neighborhood safety, access to healthcare, education, and income all shape what choices are realistically available.

“The environment really impacts one’s health, and in many cases individuals can’t do much about that,” says Rehkopf.

“While individual responsibility matters, many choices are constrained by broader social and economic conditions. As a society, we need to make it possible for people to be healthy if they want to be,” he says.

Experts agree: Even if genetics plays a larger role than previously thought, the choices you make can play a big role in adding years to your life. Perhaps more importantly, healthy choices will also maximize your health span, boosting the quality of the years you get.

Based on current evidence, scientists recommend prioritizing the basics:

• Fill your plate with plants and limit highly processed foods.
• Move your body regularly, focusing on consistency over intensity and breaking up long periods of sitting.
• Protect your sleep with regular schedules and supportive routines.
• Manage stress through realistic, repeatable strategies.
• Nurture friendships and social connection.
• Know your family history and follow evidence-based screening guidance.

Another thing they all emphasized: Don’t get too caught up in supplements, gadgets, or tests promising dramatic life extension.

When people ask him about the keys to living longer, Brenner keeps it simple: “Do more, worry less.”

• Recent research suggests that genes may account for about half of aging-related lifespan, but that still leaves substantial room for lifestyle and environment to shape how long and how well people live.
• Genetics can work in both directions: Some variants appear to protect against age-related disease, while others may raise the risk of serious conditions earlier in life.
• Physical activity, diet, sleep, stress management, and social connection all influence health span, often by reducing the risk of chronic diseases that shorten life.
• Focusing on consistent, sustainable habits rather than the latest fad on “optimization” may do more for long-term health than trying to outsmart your genes.