I would say it is pretty common that we are fascinated by differences among humanity. Some people let that fascination turn into envy and hatred, hence racism and bigotry.

I find black women both fascinating and sexy. I like how they have smaller more fine body hairs (not pubic or head hairs) than whites, the different hues of the skin from palms and bottom of their feet to the darker skin. It is this difference balanced by the obvious similarities that brings the sexual attraction in my mind.