Two teams of researchers have independently identified genes that may predispose a person to weight gain. The results confirm that gaining weight may go beyond diet and lifestyle; instead, it’s a complicated combination of many different metabolic processes, which can be effected by the genes our parents pass on to us.

In the first study, published in the journal Science, researchers at Boston Children’s Hospital studied mice and found a rare genetic mutation that prevented the animals from burning off fat calories, reports They found that within a group of obese people, the same gene was mutated. The mutation was in the Mrap2 gene, and it led the mice to consume fewer calories while gaining twice as much weight as they should have. When given the same amount of calories as a control group, the mice continued to gain weight. The researchers concluded that the mutated gene made the mice hold on to the fat rather than breaking it down for energy.

The other study comes from University College London and found that a specific form of a gene FTO, which has already been associated with obesity, can heighten the desire for high-fat foods.

The team sorted a group of 359 men with normal weight by their FTO genes; 45 of the men had the high-risk form that has been linked to increased appetite and caloric consumption. By measuring hunger hormones before and after meals, the researchers were able to conclude that the men with high-risk FTO did not show the same drop in hunger hormone levels as the men with regular FTO, suggesting that they remained hungry.

Researchers at the Harvard School of Public Health say that studies like these are making it easier to untangle the genetic factors that contribute to obesity; so far, over 30 candidate genes on 12 chromosomes associated with body mass index have been identified.

That said, we can’t start blaming the love handles on our genes quite yet.

“Thus far mutations in about eight genes are known to cause obesity in humans. But these mutations account for under five percent of the obesity in our society, and certainly are not, by themselves, responsible for the current obesity epidemic, since the mutation rate in these genes could not have changed dramatically during the past twenty years,” says Dr. Joseph Majzoub, the chief of the division of endocrinology at Boston Children’s Hospital, who was involved in the Science study.

“However, mutations in these genes have led to the discovery of pathways that are important in energy balance in humans, giving us hope that drugs can be developed that affect these pathways to prevent excessive weight gain, either by curbing appetite or increased burning of calories,” he added.

Related obesity stories on MNN:

Do we inherit obesity? New genes identified suggest we might
Blame it on the parents: Two recent studies find more evidence that genetic factors can contribute to obesity.