A new study published in the Journal Molecular Psychiatry may shine some light on why some adults have more trouble avoiding weight gain as they get older. A defective gene, a variant of the fat mass and obesity-associated protein, or the FTO gene, may be the culprit.

Researchers found that people with the FTO gene variant have reduced function in their medial prefrontal cortex, a region in the brain thought to be important in controlling impulses and response to the taste and texture of food. More simply put, the the presence of this gene makes impulse control more difficult, which can then lead to poor food choices and eventual weight gain.

According to the study, about 45 percent of adults have at least one copy of this gene variant, almost doubling their risks of being obese. Of those adults, 16 percent have two copies of the gene variant.

“Sure enough, people who carry one or two copies of the FTO variant show increased intake of high-calorie or fatty food as they age,” senior author Dr. Madhav Thambisetty, chief of clinical and translational neuroscience at the National Institute on Aging’s Laboratory of Behavioral Neuroscience told HealthDay.

But while researchers admit that having the gene adds to a person’s risk for becoming obese, it shouldn’t serve as a deciding factor for succumbing to uncontrolled weight gain. Rather, they say, the scientific finding will help future healthcare providers better address obesity risk and treatment.

“You may be genetically susceptible, but by living a healthy lifestyle you can overcome your genetics,” Ruth Loos, director of the genetics of obesity and related metabolic traits program at the Icahn School of Medicine at Mount Sinai in New York City, told HealthDay.

“You are not destined to be obese.”