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."

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.

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.

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