obese coused by friends?

Oh come on people, do anybody really believe in this nonsence? Scientists must be confused by fact that 1/3 of adults in US already have overweight and that to be fat become pretty normal there. Even having in mind that Americans are not most socializing nation, dont u think if u have few friends,chances that ur friends become obese are not so normal. I mean not so many thin and normal people left there. Besides u always feel better comunocating with people who dont look much better than u. In my oppinion first u get fat trought ur life/teenage and just than u find friends that some of tham - surprise surprise - looks similar. ( and maybe just becouse in ur villige there is no not overweighted people ) :). show me loads of people who would look for a friend just by weight. Of course there is some. But are americans sooo silly?
No surprise than when i read only normal oppinion in whole page, find out this is professor not from US.