I don't mean this to be combative, but what makes you assume it is genetics? The amount of conflicting and often known false "health" information out there makes it very likely that you just haven't tried the right change yet. Try cutting out polyunsaturated fats and using coconut oil for cooking. PUFA are broken down into toxic free radicals by lipid peroxidation. Long term exposure to these free radicals causes hormonal problems including thyroid dysfunction, insulin resistance and leptin insensitivity. Eliminating PUFA and upping your anti-oxidant intake is much easier than most other diet options as long as you cook for yourself. Unfortunately it is essentially impossible if you want to buy pre-made food as almost all of it contains "vegetable oil".