Genetics Vs Lifestyle: If Living Healthy is So Important to Longevity, Why Do Some Unhealthy People Live so Long?

Agnes Fenton of Englewood, New Jersey, celebrated her 110th birthday in 2015. For about 70 years, she followed a daily ritual of drinking three Miller High Life beers accompanied by a shot of Johnnie Walker Blue Label scotch. This routine began after a doctor advised her to drink three beers a day following a benign tumor diagnosis. Remarkably, Fenton maintained this habit for decades and attributed her longevity, in part, to this practice, as well as her faith. Fenton died at the age of 112, 2 years later.

Another real-life example of a supercentenarian (people above the age of 110) who defied conventional health advice was Richard Overton (1906–2018): Richard Overton, recognized as the oldest living World War II veteran, like Fenton he lived to the age of 112. Despite health advisories, Overton enjoyed adding whiskey to his coffee and smoked approximately 12 cigars daily. He attributed his long life to these habits, along with maintaining a positive outlook.

Now, should you follow Fenton’s lead in an effort to live longer?

Probably not.

If some people can spend a lifetime ignoring health advice and still reach 100, does that mean the rest of us are wasting time leading healthier lifestyles?

Of course not.

The answer isn’t black and white, but new research shows that while genetics do play a role, lifestyle is the far more powerful factor for most people.

Amazing stories such as this can make one wonder if beer, whiskey, and cigars are the secret to immortality. But for every Richard Overton, there are thousands whose heavy drinking and smoking cut their lives short. The real lesson is, genetics might deal a decent hand, but lifestyle determines how long you stay alive.

The Science of Aging: Environment vs. Genetics

For decades, researchers have debated the role of genetics versus environment in determining lifespan. A new study has added weight to the argument that lifestyle choices—not genetic luck—are the biggest influence on how long you live.

Scientists analyzed data from over 490,000 people in the UK Biobank, a vast collection of medical histories, genetic sequences, and lifestyle information. To understand biological aging, they focused on a subset of 45,000 participants whose blood samples underwent proteomic profiling—a process that examines thousands of proteins to estimate a person’s “proteomic age gap,” or how fast they’re aging compared to their actual age.

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Austin Argentieri, the lead research fellow at Massachusetts General Hospital and lead author of the study, explains that they can estimate how quickly or slowly each participant is aging biologically compared to their chronological age. This gap is a strong predictor of mortality and associated with aging traits like frailty and cognitive function.

The results were staggering. Lifestyle and environment accounted for 17% of disease-related deaths, while genetics explained only 2%.

Among the biggest risk factors:

Smoking, which was linked to 21 diseases
Socioeconomic status (income, neighborhood, employment), tied to 19 diseases
Lack of physical activity, which influenced 17 diseases

In contrast, genetics played a more significant role only in diseases like breast, ovarian, and prostate cancers, plus dementia. But for heart disease, lung disease, and liver failure—some of the most common killers—lifestyle factors far outweighed inherited risk.

Why Your Environment Starts Shaping You Early

One of the more unsettling findings? Your environment starts determining your longevity long before you’re thinking about it.

Children who were overweight by age 10 or had mothers who smoked during pregnancy had a significantly higher risk of disease and early death decades later. At the other end of the spectrum, factors that extended lifespan included being financially comfortable, having a stable job, and living with a significant other.

According to study co-author Cornelia van Duijn, an epidemiology professor at Oxford Population Health, the research shows that many health risks can be reduced through individual choices or policies that improve socioeconomic conditions, curb smoking, and promote physical activity.

Can Lifestyle Choices Add Decades to Your Life?

A separate study of 276,000 U.S. veterans found that adopting eight healthy habits could add up to 24 years to a person’s life. These habits included:

Eating a nutritious diet
Exercising regularly
Sleeping well
Managing stress
Avoiding smoking, opioid abuse, and excessive drinking
Maintaining strong social connections and relationships.

Those who followed all eight habits had a projected lifespan of 87 years, nearly a decade longer than the U.S. average. But even if you do everything right, making it to 100 still requires some genetic luck.

What About the 100-Year-Olds? The Genetics Exception

If lifestyle matters so much, why do people like Richard Overton seem immune to these habits?

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While lifestyle dominates the conversation about aging, genes do matter—just not as much as you might think. Scientists estimate that about 75% of lifespan is determined by lifestyle and environment, with genetics making up the remaining 25%. But once you hit 100, those numbers start flipping.

Centenarians with exceptionally long lives often don’t live healthier lives than the average person, and yet, they live longer and have lower rates of age-related diseases, like dementia, heart disease, and cancer. Many of them smoke, drink, and avoid exercise. So what gives?

Studies have revealed that many people with exceptionally long lives don’t have healthier habits than the average American. And yet, they live longer and have lower rates of age-related diseases, like heart disease, cancer and dementia.

Genetic studies show that long-lived families often share rare gene variants that protect against multiple age-related diseases. The APOE gene, for example, is a well-documented factor in Alzheimer’s disease. People with the APOE4 variant face a higher risk, while those with APOE2 have a lower risk. Families with exceptional longevity tend to have a greater prevalence of the protective APOE2 variant compared to the general population.

Beyond disease risk, some genes may directly impact the aging process itself. One standout is FOXO3, a gene consistently linked to longevity in studies of centenarians. It plays a crucial role in maintaining cellular health, influencing processes like stress resistance and DNA repair. Because genes like FOXO3 affect aging at a biological level, Dr. Milman suggests they may help guard against multiple age-related diseases, not just one.

A study by Dr. Barzilai and his colleague Dr. Sofiya Milman found that even when centenarian offspring had unhealthy lifestyles, they still had low rates of cardiovascular disease, these protective genes seem to offset the damage—unlike the general population, where bad habits are far more deadly.

But these longevity genes are incredibly rare. Less than 1% of people have them. Unless you know you hit the genetic jackpot, lifestyle choices such as exercise, healthy eating, and not smoking still matters.

Living Like Your Genes Don’t Matter

It’s tempting to think that drinking beer every day or skipping healthy foods is won’t have much effect just by listening to the amazing stories of people who lived to 110. But that’s survivor bias—we sometimes hear from the ones who got lucky, not the millions who didn’t.

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As Dr. Thomas Perls, a longevity researcher at Boston University, puts it: “Having the right genes is like winning the lottery. But even if your mother made it to 100, you should still practice healthy habits—just in case you didn’t hit the jackpot.”