NEW ORLEANS — Clean living can slash your risk for heart disease even if your genes are heavily stacked against you. A large study finds that people with the most inherited risk cut their chances of having a heart attack or other heart problems in half if they didn’t smoke, ate well, exercised and stayed slim.

The opposite also is true: You can largely trash the benefit of good genes with unhealthy habits.

“DNA is not destiny, and you have control,” said the study leader, Dr. Sekar Kathiresan, genetic research chief at Massachusetts General Hospital. “Many people assume that if your father had a heart attack, you’re destined to have a problem,” but the results show that’s not the case, he said.

The study was discussed Sunday at an American Heart Association conference in New Orleans and published online in the New England Journal of Medicine.

It’s long been known that genes and lifestyle affect heart risk, but how much influence each one has, and how much one factor can offset the other, are unknown.