The area of China where I live tends to the spicy (sometimes very), yet children eat the same as their parents. They soon get used to it.
Also, I have never seen a children's menu in a restaurant in China. Again, everyone eats the same irrespective of age.
Nor have I ever heard a parent complaining that their child is a 'fussy eater'. In fact, I've had trouble trying to explain the concept to Chinese people.