Even if members of your family are fat — that does not mean that you have to be overweight.

British researchers say that genetics is not an excuse for obesity. They add the key to staying slim is to get plenty of exercise. Their findings were released Tuesday in the journal Plos Medicine.

Gil Atzmon, a geneticist at the Albert Einstein College of Medicine in the Bronx, N.Y., said the findings underscore that DNA doesn’t necessarily mean destiny.

“The message from this is, if you have a genetic predisposition for some things, you can change your lifestyle and contribute to better health,” he told the Los Angeles Times.

You do not have to run a marathon. All of the exercise you need is some form of daily activity for about one hour a day.

However, people who are predisposed to obesity should take in a little more exercise. That could be something as simple as walking a dog or working in a garden.

Scientists say studying a person’s genetic makeup may one day help to better treat obesity with tailored treatments for that particular individual.