Genes vs. Lifestyle: What Matters Most for Health?


Does an illness like heart disease or cancer run in your family? Don’t assume that your genes control your destiny. Experts say the lifestyle choices you make every day can help keep you healthy.

There’s no doubt that some genes do lead inevitably to disease. “But for most people, a healthy lifestyle trumps inherited risk,” says cardiologist Donald Lloyd-Jones, MD. He is chair of preventive medicine at Northwestern University Feinberg School of Medicine. “Even if a disease runs in your family, there’s a lot you can do to avoid it.”

Did You Know?

Under the Affordable Care Act, many health insurance plans will cover preventive care services, including checkups, vaccinations and screening tests, at no cost to you.

Here’s a look at how lifestyle changes can cut your risk of disease.


About 25% of colon cancers are in people with some family history of the disease. In the rest of people who get colon cancer, genetics doesn’t seem to play a role.

But lifestyle may be a factor. Studies show that most people can dramatically lower their colon cancer risk by taking these steps:

  • Eat very little red or processed meat.
  • Exercise.
  • Keep a healthy weight.
  • Drink alcohol in moderation or not at all.
Other cancers are even more influenced by the choices we make. A good example is lung cancer.
  • 80% to 90% of lung cancers are caused by smoking.
  • Men who smoke are 23 times more likely to develop lung cancer than nonsmokers.
  • Women who smoke are 13 times more likely to get lung cancer.

The longer you smoke and the more cigarettes you smoke, the greater your risk.

Still, genes do play some role. Some people who get lung cancer never smoked. Other people smoke and don’t get lung cancer. But the biggest risk factor by far is smoking.

Heart Disease

With heart disease, more than 100 types of genes may play a small role in a person’s risk, Lloyd-Jones says. “But by far the biggest factor is lifestyle.”

Lloyd-Jones and colleagues analyzed data from the Framingham Heart Study. The study followed three generations of families. The researchers found that:

  • Family history made up only 17% of a person’s heart disease risk.
  • Poor lifestyle choices, such as lack of exercise, made up a whopping 83% of the risk.

A heart-healthy lifestyle can lower your risk of heart disease.

For example, one type of gene strongly linked to heart disease is called 9p21. On average, it raises your risk of having a heart attack by about 20%.

But if people who carry this gene eat a diet with lots of fruits and vegetables, research shows, they cut their risk back down to normal. People with that type of gene who eat a poor diet, on the other hand, have two times the normal risk of having a heart attack.


Type 2 diabetes is influenced by a combination of genes and lifestyle. Between 30% and 70% of the risk of developing type 2 diabetes is shaped by inherited genes.


But genes only tell part of the story. The U.S. has been in the grips of an obesity epidemic in recent decades. It’s been fueled by inactive lifestyles and too much high-calorie food. That, in turn, has helped bring on a rise in type 2 diabetes.

Exercise and weight control can lower your risk of type 2 diabetes. In one ongoing trial, researchers are testing an intensive lifestyle program that encourages:

  • Exercise
  • Nutritious low-calorie food choices
  • Weight loss

Volunteers in the program have seen dramatic improvements in their A1C levels, a blood test used to check diabetes risk. Blood pressure and cholesterol levels have also improved significantly.

It’s Not Too Late to Start

The earlier you adopt a healthy lifestyle, naturally, the better. Lloyd-Jones and his colleagues recently completed a study on heart disease that looked at lifestyle factors in people who were about 25. The researchers checked in with the study participants 20 years later. People who kept a healthy lifestyle into middle age were far less likely than those who didn’t to have risk factors such as high cholesterol and poor blood sugar control.

Still, it’s never too late to start. People who make healthy changes even as late as their 60s and 70s see dramatic reductions in risk, according to research by Richard S. Rivlin, MD. Rivlin is a professor of medicine at Weill Cornell Medical College.

By exercising and following a healthy diet, older people can lower their risk of both heart disease and osteoporosis, or bone loss. Adults over 65 who already have coronary artery disease can lower the danger of heart attacks by as much as 45%, Rivlin found. A low-calorie diet and regular exercise among older people can cut the risk of cancer nearly in half.

Genes play a role in our health, so it’s important to know your family medical history to understand your personal risks. “But for most of the chronic diseases that plague us, from heart disease and stroke to diabetes, lifestyle still trumps genes,” says Lloyd-Jones. “Staying healthy is still mostly a matter of the choices we make.”

February 16, 2014 |

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