black
live and let die.
That was fairly early. If you're not aversed to dating out in highschool, you wont be in later life. Your expectations for a partners may change, your tastes probably wont. My point was, I've been seeing it since early and it isn't a weird sight.
People's reason for not dating out isn't always tied to preference or taste. For lack of a better word, dating gets more 'politicized' as you get older. In school, very few people would even care at all about things like cultural stigma.