DS1 is 4.4yo, and is - as far as I can tell - perfectly normal and healthy.
One thing he is though, and more so than I've seen any of his friends or peers, is shy.
At parties he won't play with the other kids really unless his two closest friends are there.
He never greets anyone or says good bye. We tell him it's polite to reply to someone when they say hello or goodbye but he just ignores us.
We recently had DP's parents to stay for two weeks and DS1 wouldn't even wave or acknowledge them as they left.
Every morning his teacher says "good morning" and he doesn't reply. All the other kids smiled ans say hello back. He tells me he says it back to her quietly or "I say good morning at the register mummy"
He never says hello or answers any adult who talks to him like the parents of his friends or my friends if we meeting up with them etc.
Does this all seem within the realm of 'normal'....?