I knew 2 people long ago, 1 male 1 female that were passing as white. The man looked hispanic, although his mother was caucasian and his father black.
The woman was fair skinned, mother caucasian, father black.
When I asked the woman why, she did not want to be known as bi-racial, she in essence said she did not need the baggage that being bi-racial entailed.
When I asked the man same question, he indicated that he would rather make his way without all the crap that went with being black.
It depends on the person - I have a roommate who’s a mix of Asian, Native American, and Caucasian and she technically idenitifies as ‘multiracial’, but she’s all about the asian side of her heritage, and if you were to just look at her she appears asian. Another ex-roommate of mine was equal parts American Indian, Middle Eastern, African-American, and Caucasian, but she usually said she was Middle Eastern and seemed to identify with African-American ‘culture’ the most, and she looked more or less African-American to the casual observer.
In any case, most mixed girls tend to be really gorgeous... at least from what I’ve seen, being mixed tends to give some sort of ‘fashion cred’ and the ‘omigod, you look AMAZING, I wish I was half as good-looking’ comments seem to outweigh any baggage about racial identity that might occur (at least for girls).