My 2.5 old boy is not greeting to my relatives and friends. Is it normal?

Hi,
My 2.5 year old boy is a typical boy that I normally don’t worry. When he was around 2, I noticed that unless my friends offer him candy something to get his attention, he just played with himself or some other kids. By offering candy to ask to get a hug or kiss, that’s the only way he does it. Grandpa and grandma came to see us during the holidays and he doesn’t even say hi to them. Is this normal? Or did I do something wrong?
Thanks!
Julie