Yeah, this kind of discussion is why EQG used Amazing Technicolor Population: to avoid any discussion over what race a given character "should" be (as one of my lower comments states, if you think it even matters whether a character is black or white, you're an asshole). When thinking it over, I realized that, of the Mane Six, we only have three unknown parents: both of Applejack's (who are heavily implied to be dead and therefore unlikely to appear, and it'll only ever be implied because parents nowadays seem to think kids can't handle the concept of death) and Rainbow Dash's mother (it's been theorized in some places that it's Daring Do, but not actually known).