Even if this wasn't sarcasm, it doesn't work. Statistics already prove this when you track the offspring of "good" immigrants. There's a reversion to mean in all races when they have children. And yes, there's also eugenics such that good people may improve the genetics of their offspring but there's also variation and reversions to mean.

Overall, when you analyze the data, the only correct move is to not allow people who aren't your race into your society.