If your mom and dad are apple-shaped, it’s easy to say you’re “destined” to have a tummy because of fat genes and use this excuse to eat fast food or skip working out. And while new research seems to back this up, I’m not so quick to believe it—and you shouldn’t either.

Scientists at the University of California, Los Angeles fed a group of genetically diverse mice a normal diet for eight weeks and then switched them to a high-fat, high-sugar diet for eight weeks.

While the unhealthy feed caused no change in body fat for some of the rodents, others’ body fat percentages increased by more than 600 percent! Having identified 11 genetic regions associated with the development of obesity and fat gain—so-called “fat genes”—the white coats say the difference was largely genetic—some mice just were born to gain more on a high-fat diet.

Read the whole article published on Shape.com here.