Don’t shoot the messenger – this is the biological reason of why mixed-race people appear to be more attractive than other races. It may not apply to the majority or as a long-term thing. But in terms of seeing someone for the first time & those first moments of attraction, this is the answer.
Attraction is not subjective as some people think. It is objective. People on average prefer people with more symmetrical and average features. Not average as in what is “averagely” attractive – but lips for example – if you took all the lips in the world & found out what the average lip is, mixed-race people are more likely to have them. For example, take the extreme of a very “white” lip (usually associated with being very thin) and a very “black” lip – if they reproduce, the lips of the mixed child will be “average”. Not too big, not too small.
The reason for this attraction towards more average things is because it is “easier” on the eye in a sense. Someone with a lot of complex features – take someone like Kate Moss for example, when we look at her we have to pick her features apart to see her “beauty”. For a mixed-race person, because most of their features are more average or “generic” (think of the Sims) it is easier to “take in” all of their features at once.
As a side note – I know Megan Fox isn’t mixed race but she has been counted one of the more beautiful women in society multiple signs & scientists believe this is because her face is very symmetrical.