Is it wrong to hang out with 16 year olds if you're 13?

I hang out with people that are 12 - 15 years old,(Mostly girls), however, we do han gout with one 16 year old guy. I swear, he's the nicest person on earth! I look up to him as an older brother, since I don't have any siblings,('cept my 25 yr old brother thats in another state), and my deceased sister. So I just have that need to have an older guy and girl to hang out with, and call my 'brother I never had', He looks to me as his little sister! Problem is, my dad gets soo mad when I text, talk, or hang out with him, even when we all hang out in a group. I don't see what's wrong, were just friends, I don't plan on dating him anytime soon, we just have a brother-sister friendship.