Seen...
There's a science fiction-kinda story by this guy Terry Bisson (who happens to be white). It's set in a future where ozone depletion has continued. The government make it illegal for black people to marry each other, they are forced to marry white people so they can pass on the melanin to the children. Gov't say "melanin is a precious genetic resource" that must be used for the benefit of all people, not "selfishly" by blacks alone. The main character in the story is a black woman who wants to marry her black boyfriend but they won't let her. When she starts to protest the white social worker points to a picture of Martin Luther King on the wall and says "MLK died to stop racial separation and hatred! Stop your bigotry and go marry so-and-so white person!"

Obviously the story is a satire and not meant to be taken entirely seriously... but it make you think... today's science-fiction satire could be tomorrow's reality...