Ehh. I think most stereotypes have at least some truth to them. Koreans have, statistically, the smallest ding dongs. Lmao... anyways, I think that would depend a lot on how you define 'smart'. I'm pretty sure that they are better at math. And the kids do better in school, but thats probably because of how hard the parents push them. So maybe its something with their brains, maybe it's just cultural, probably some of both.
I don't think Chinese people are naturally smarter than other people. However, many people that come from different places tend to try harder than most Americans. I think it's because some of them feel they have to prove themselves.