I can see how, for some people, aspects of one particular race might play more of a role in sexual attraction than the same aspects of another race. Eyes, lips, facial shape, hair colour, hairyness(!) and yes, even skin tone. I don't see anything wrong in recognizing that these things can result in a greater preferences for people of one ethnic background over another. The key is to make it clear that this is "in general" and to think about how we express this preference (possibly a bit more measured/polite than "black girls are hotter than chinese girls"

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In my case I genuinely don't feel any less attraction for one race than another. I know some people do, and that's fine. There's a phrase some gay men will be familiar with called 'rice queen' - white dudes who are only or mainly attracted to asian (Chinese, Korean, etc) guys. My partner is a different race to me but I'm not more attracted to his race than other races. He could quite easily have been white, black or anything in between.