Sorry I'm gonna have to disagree with you there. Saying someone's race will be "extinct" if they "interbreed" is reminiscent of Nazi philosophy. Rejecting human beings in order to keep your race "pure" is practically the definition of racism. Culture and heritage have nothing to do with DNA. Very few people in this country or elsewhere are "purebred" anything.
I don't believe that was his point, but I'll let Vader speak for himself. Just because you want to keep your heritage automatically makes you racist? Interesting times we live in.