It probably isn't, but appears so.... Children learn their eating habits, from their parents, if the parents over eat and under exercise, then the child learns this behaviour. This is why it appears that obesity is genetic. Because when you look back at the last 4 generations, they are all heavy.

Where genetics comes into play, is that it's a handy way to avoid taking responsibility for the situation, a common theme in today's North American society. "I can't help that I am fat, it's in my genes" is a good way for the obese person to avoid taking responsibility, and to avoid taking action.