So he hasn't had alot of family bonding time with you guys then? When I was 21 I had alot going on in life too, and was probably neglectful of family contact too.
Just keep trying to love him and maybe try to tell him you wish you guys had a stronger realationship, because to you it seems, that you've done something to offend or distance him. Keep the focus on your open nonjudging feelings of love for him, that you already have, and off the judgemental you you yous.....this doesn't work nearly as well.
My Mom always said you catch more flies with honey than vinager....I don't know why Mom was always trying to catch flies, because she said this alot
Good luck Bearsy. I hope you get the realationship back to talking terms, or perhaps take the conversation to where he is and edge him out of it over time. Just stay interested in his life as much as you can, with your feelings and health in mind as well.