without knowing much information, i am jsut guessing. Correct me if i am wrong.
from cognitive point of view, his concept or thinking may have influenced his behaviors. Some Chinese American kids (different ages) experience some "identity confusion", becauuse they are exposed to two different cultures on daily basis, from languages, food to many other aspects.
in terms of eating, maybe many of his friends at school eat Burgurs, Sandwichs, and pasta, so he thinks this is the "normal food", while Chinese food is outside the range. he may think by eating Chinese food will make him "less American". (some kids feel that). they also have "peer pressure". they try to copy their peers' behaviors in order to "fit in".
How about this? Try to invite some of his best friends and their parents to home and feed them some delicious Chinese dish. If his friends all like it, maybe he will slowly learn to like it too, and accept it. Not sure it works, but may be worth to give it a try.
if he still doesn't like it, then let it be. Just want to make sure this eating problem is not the expression of other hidden problems.
