Fundamentally, even ignoring the ethical problems, eugenics doesn't work. The interactions between nature and nurture, genetics, epigenetics, etc. are waaaay to

Fundamentally, even ignoring the ethical problems, eugenics doesn't work. The interactions between nature and nurture, genetics, epigenetics, etc. are waaaay to complex (and even multi-generational) to boil down to a simple decision to allow/deny birth.