·People with 1 copy of a specific gene variation had 30 percent higher obesity risk.
·Those with 2 copies had 70 percent higher obesity risk than those without.
·Researchers don't know how the gene works.

Scientists from the University of Oxford and Peninsula Medical Center in Exeter have found another gene that may "keep you from fitting in your jeans," according to the journal Science on Friday.

Gene has long been assumed to play a role in making some people fatter than others, and previous research has tentatively implicated specific genes.

Scientists don't blame this gene, named FTO, for all the extra inches. They discovered that people who carry two copies of a variation of the FTO gene weigh, on average, about 3.5 kg more than people who lack it.

Unlike other genes thought to be involved with appetite or calorie burning, scientists have no idea yet what FTO is supposed to do.

But the study shows strong evidence of a link. Using blood samples provided by more than 38,000 people, scientists have found that those who had one copy of the gene variation had a 30 percent increased risk of obesity, and carriers of two copies had almost a 70 percent increased risk.

The gene's effect was seen by the age of seven, it said.

The study included mostly white Europeans, and about one in six of them are thought to carry two copies of the gene variant.

About a third of American adults are obese, and millions more are overweight. Bad diets and too little exercise are the chief factors. But innate biology plays some role, and researchers are exploring a variety of genes and hormones that seem involved in the balancing act of weight gain and loss.

(Agencies)