I would start asking your parents questions and look at what you were like before you were being sexually abused by your perp brother. Were you overweight as a little boy? If you look to food as a coping mechanism, I would put about 99% of the blame on that perp brother of yours, if you were ALWAYS overwieght and simply never addressed it as you grew older, then I would put a little more blame on yourself. Were you always overweight Jason?
No, I wasn't always overweight, as a matter of fact there was a point in my childhood (somewhere between 7-10) where I had bad allergies and my mother took me to all these doctors and I was put on a rather strict diet (including no food coloring, etc) and I was "as thin as a rail". As a matter of fact, I was drinking Snapple before snapple was popular, they had a colorless rootbeer ("Tru Root Beer"), that I had to get from a healthfood store. That didn't go on too long as we weren't seeing any difference and she couldn't bear to make me eat like that. I regained normal weight and I think it wasn't until high school (my abuse took place in 7th grade) till I started to really started to become overweight. I do believe I use it to cope, when I'm depressed, bored, etc. So I guess your 99% blame to my brother would be accurate.
But as everyone else is saying, I need to take responsibility to getting myself back to normal weight again