Bullying is a problem, but I don't think there's ever been the kind of organised hatred against fat people that there has been against, say, blacks - look at the KKK. Admittedly a pop-culture that tells everyone they're overweight if more than skeletal and encourages them to take on the latest fad diet is tough on plump people, but nobody campaigns to "send those fat folks back where they came from". I think the principle difference is that many people have fat friends or at least relatives, whereas many white people have no black relatives and if they choose can associate only with other whites. That kind of strengthens the 'us vs them' barrier. Children have minds? I mean, 'course they do, but they're still very easily influenced by what their parents believe... whether more so than adults are by their peers I'm not sure, but at least adults have more choice of peers than children do of parents.