What is the main influence in obesity and weight gain? Is it the genetics or is it the environment? The question is a very important one to answer, since if it was 100% genetic, no amount of diet and exercise would be able to help, if it was 100% environment, then everyone with weight problems could be blamed for being irresponsible and lazy. However, turns out that the reality is not black and white but rather in between, and nowadays we have a lot more information and understanding on the subject.