Kids are saying,things such as you fathers not Thai so he's no good,
I remember reading my neice's kindergarten Thai book a few years ago when I was learning to read Thai, it was full of pages about how simply great Thai people are.
Page after page of stuff like 'Khon Thai bpen keng keng'. (Thai people are very strong) each repeated about 10 times.
They're simply conditioned since birth that they are superior and greater than others.
A lot of the deep lying resentment and hate for Westerners here is the glaring reality that that is simply not the case, and their inability to deal with it.