I brought a family member over to my house. One of my roommates was home and my relative smiled at him, said hi and waved. He just stood there and stared without waving back. He definitely saw and heard him. It would make me feel better knowing why he didn't say hi back. How can I ask this without sounding confrontational? I know some people can be shy but not even waving back is a bit much.
The roommate is in his 20s and belongs to Filipino. His English is fine. FWIW all Filipino people I've met have been very friendly and good in social situations so I doubt it's a cultural thing.