Found, the gene that makes a third of women pile on the pounds: Mutated DNA strand can increase chance of gaining a stone Gene affects women - not men - making them more likely to gain weight Ladies, if you're having trouble squeezing into your jeans ... blame your genes. The hereditary material that leads to women - but not men - putting on weight has been identified by scientists. Almost a third of women are thought to have a mutated stretch of DNA that fuels the development of fatty tissue and makes those with it two and a half times as likely to put on more than a stone. It's in my genes: Women who have the strain of mutated DNA are two and a half times more likely to put on a stone or more But before the men start sniggering, scientists say they have their own rogue "fat gene" that can cause them to binge on high-calorie junk food. The discoveries offer hope for the future creation of tests to pick out those at highest risk of losing the battle of the bulge. Researchers at Maastricht University in Holland followed the weight gains and losses of more than 5,000 men and women for ten years before analysing their DNA for genes that have been implicated in obesity. They found a mutated version of a gene called MMP2 to be common in the women - but not the men - who had gained weight. Scientists found a mutated version of a gene called MMP2 to be common in the women ¿ but not men ¿ who had weight problems Researcher Dr Freek Bouwman said that at least 30 per cent of women have the impaired version of MMP2. For men, a flawed version of a known gene called FTO makes them pile on the pounds, with those carrying it almost twice as likely to have gained more than a stone. Dubbed the "junk food gene," it increases cravings for sugary and fatty foods and men who have it can eat about 100 calories more per meal than average - the equivalent of a small Kit Kat or a bag of Wotsits. Over a week, the extra food eaten amounts to 2,100 calories - or an entire day's food. FTO and MMP2 may be gender-specific because their activity is controlled by sex hormones, the European Congress on Obesity in Liverpool heard. Delegates were told that the findings could also help one day identify people who are particularly prone to putting weight back on once they have lost it. Professor John Wilding, of the UK Association for the Study of Obesity, said genes cannot take all the blame. People should still worry about what they eat, he said. You can't change your genes, but you can change your behaviour.