For people who struggle to stay away from unhealthy chips and burgers it may be the perfect excuse. Scientists have found a gene mutation that makes fatty foods irresistible and even causes carriers to reject low-calorie versions of the same meal - even when it looks and tastes identical.To find out if there was a genetic link to food preferences, researchers at the University of Cambridge hosted an all-you-can-eat chicken korma buffet for 54 people, 10 of whom were carrying the defective gene.They provided three versions of the curry, which tasted the same but had a different fat content, and allowed participants to sample each dish without telling them which was the most calorific.Researchers found that, although there was no difference in the amount of food eaten, individuals with a mutation in their MC4R gene ate almost double the amount of high-fat korma than lean individuals and 65% more than obese individuals.Researchers said: "By carefully testing these nutrients separately in this study - and by testing a relatively rare group of people with the defective MC4R gene - we were able to show that specific brain pathways can modulate food preference."..