I don't know who my genetic grandparents were (both parents were adopted my mother has no clue who her genatic family is and all i know about my dad's side is his dad was an acholholic and his mother had mental issues and that was genetic cause him and his brother both have them) but my parents adopted parents were really thin, my mom was thin until she got away from her mom who kept her on diet pills from the time she was 7 or 8 and she gained weight really fast her metablisom is so screwed up and she has so many health problems that can be traced back to that. my dad has always just been a big guy.
anyways I think more then anything it was the diet (or lack there of) that I ate as a child not genetics that made me gain weight.. that and just not caring about myself - alot of depression.. I was active but I hardly ate, when I did I ate to much and mainly cheap foods like ramen noodles and such