In the U.S., childhood obesity has more than tripled in the last 30 years and everyone from the food industry to parents to school lunch providers have been dished their fair share of blame.

While environmental factors can have a profound effect on children’s weight, researchers also know that genes increase susceptibility to weight gain, and in a recent study, scientists found two gene variants that appear to play a large role in predisposing some children to obesity more than others.

“It is clear from our research that there is a genetic signature to childhood obesity. This should motivate us and other researchers to uncover further genetic components to the trait,” says the study’s lead author, Dr. Struan Grant, associate director of the Center for Applied Genomics at the Children’s Hospital of Philadelphia.

Previous research on the genetics of obesity has focused on variants that are associated with extreme obesity in children and adults, but the new study isolates genes involved in common obesity — the kind we normally attribute to sloth and overeating.