What if it is a compromised child ?
Nothing to pity on these parents, where I can't help when a child misbehaves in a supermarket and parents stand there helpless. Later in another few minutes, people around them start to note the subtle abnormality in the behavioral of the child. Mother starts to feel uneasy and takes quick look around to manage the situation, but in vain.......................
Normal behavior in children depends on the child’s age, personality, and physical and emotional development. A child’s behavior may be a problem if it doesn’t match the expectations of the family or if it is disruptive. Normal or “good” behavior is usually determined by whether it’s socially, culturally, and developmentally appropriate. Knowing what to expect from your child at each age will help you decide whether his or her behavior is normal.
Some answers are not blatant in the real world, though it is the child's own parents who had dealt with them all the while. So to seek help will be to a developmental pediatrician.