I think people get judged when they are different. Doesn't matter how old you are either. When groups of people collect together in a social setting, and someone different comes into it, it seems to be an innate protective measure to push away and estrange the person that is different coming in. Whether they are afraid the person is going to mess up the dynamic or change things when they don't want them changed, who knows?
Jr. High (those tween and early teen years) are horrid because the kids are in the midst of a very insecure time themselves. So they collect with folks that are like them. You don't see the cliques starting until Jr. High - and I think this is why...You clique with who you are like and you belittle those that are not like you to make yourself feel better.
I have seen adults do the same thing though. It's unfortunate that people do it but I think Ceili is right - it seems to be part of human nature.
Didge has a point in that learning to deal with it - knowing who you are and being happy with it is all that matters. Realizing that those that judge and make fun of you, are insecure and do not have a good grounding in their own belief in who they are and that may help you deal with it...because - you may move eventually - but you may come upon it again. Best to know who you are and to be true to it.
Best advice - figure out why you do what you do - if you are happy with your reasons...stick with it and count the ones that criticize and judge as the ones with the problem.