V.L.
I don't see this as being not normal, but he would probably benefit from having a more social life with friends his own age. Is he involved in sports teams at school? Or Little League in the summer? How about a bowling league for kids his age? Boy Scouts? If you got him involved in things like these, he would make some friends and have activities with kids his age.
At the same time, at least you do not have to worry about him having inappropriate associates. Be grateful he is close to the two of you.