Just reassure him that this happens to all teens. Bio or adopted, makes no difference. His other potential parents could have been weirder, less weird, down right nasty, or great "regular," 3 dogs and 3 kids, suburban family. The reason they adopted is probably because they are deep down nice and caring people. Just point these facts out to him. I was artsy, reading, into classical music teen, and my parents are none of that. It is all about love and care, and this is the right age for him to start accepting people for who they are.

Barker adoption foundation has a teen group, I think. Or maybe just a teen retreat.
You could call and see if they have a support group available that might be right for him.
You don't need to be adopted through Barker to use their post placement services

My adopted teen is "different" than us. She has different interests, different strengths, different weaknesses....

We try to celebrate those "differences." For example, she is really into a particular sport and the rest of us have learned about it.

Based upon my experience, I would tell this teen to try to bring his family into some of interests. If they are not interested, maybe you could be the adult that talks to him about his particular interests or even goes a step further and helps him explore those interests and even "celebrate" those interests like "wow! you are very knowledgeable about that!"

I was not adopted, but often felt like I was adopted. As I got older, I found commonality with my family. Tell him even bio kids can feel out of place. Don't envision the life that could have been. Enjoy the little happy moments now. Love that family has hard as your can. That is your family.