>>211647848 (OP)Being "mixed" doesn't automatically makes you attractive since everyone is mixed from different ancient groups. But if you look different from your partner, it indicates that your offspring will be less inbreeded.
For example:
1. Not the main factor but the easiest to observe. Being inbreeded makes you ugly like some old European royalty or American "rednecks".
2. The main factor is the transmission of "bad genes" like predisposition for blindness. If we look at big cities, we'll find millions of people with predisposition for blindness but they're are less likely to meet each other than villagers with the same predisposition.