Whats wrong with my brother?

He can be loving sometimes but I find him extremelly weird. He's really peverted like he would just slap my ***, or my dad's , and even my mom's or even squeeze it. He would just say "butt slap" or butt in spanish which is "culo". Or sometimes he would go up to my dad and poke his nipple and say "nipple" like a little kid. Once in a while he would go up to me or my mom and poke us on our nipple and say "boobie" like a little kid. I know I shouldnt be letting him do that to me but it just happens so fast and quickly when he does something like that and it's really annoying. But he usually does all that stuff to be funny but to me he's just being a pain in the ***. But is he normal? Do you know any guys who act like him? Is there something wrong with his brain (he's in esl too just saying , i'm not trying to be rude but it's true) ? Is it normal for some guys to act like this? Is there something wrong with my brother? I mean like he is a normal guy like he has friends and have this guyish attitude and be really cool but his pervertness is just.... Is there something wrong with him?(i swear i asked that question twenty gazallion times but I'm asking it again? I'm getting worried and a bit scared. :O