Eugenics movements of the past based on pseudoscience (physiognomy, anyone?) were pretty ugly.
Based on our ability to learn from the past, I’d say the future eugenics movements based on actual science might not be much better. Gattaca was a good story, but it was conspicuously bloodless.
On a related note, ESR is beginning a series of posts examining the main ideas of the Dark Enlightenment. His take on genetics/human-biodiversity and how they play into science and the political spectrum is dead-on:
Another way the DE puts this complaint is that nobody on the conventional political spectrum takes Darwinism seriously enough. Left-liberals self-identify as the friends of evolution out of a desire to be “on the side of science”, but if they really understood the implications of evolutionary biology and psychology they would be more horrified by them than Christian fundamentalists are.
And because comedy helps put things in perspective: Louis CK on Nut Allergies