My sister is dating a black guy?

My parents do not approve, because he is black. I feel awkward about but I'm not against it...My mom and dad says there are many white men available then someone like him. Also, his family don't seem to like my sister at all (I met them picking her up from his house). My sister rebelled and ran away to his house. Should I get my parents to see more liberally or tell my sister to stop dating the black guy.