I'm positive you're wrong about that; you haven't seen *EVERYONE* in the world.

But.... here's my copy&paste for every time this question about "I'm only attracted to [ethnicity]" comes up:

You like what you like; it's nobody's business. However only you deep down inside know the REAL reason; if it's racism or if it just happens to be your preference. Maybe in the grand scheme of things it doesn't matter but you can easily cause trouble for yourself by going around announcing your preferences to people who didn't ask you. You should also avoid shaming/insulting people that don't fit your preference. Just go out and live your life. Don't overthink it; don't needlessly mention your preferences - nobody really needs to know. The only possible exception is on your dating-profile and there are subtle ways to hint at what you like without being a bigot/jerk.