After finding out that Thomas Jefferson owned slaves, I guess nothing of this sort disturbs me anymore.

According to wikipedia's entry on Eugenics:

The philosophy was most famously expounded by Plato, who believed human reproduction should be monitored and controlled by the state. However, Plato understood this form of government control would not be readily accepted, and proposed the truth be concealed from the public via a fixed lottery. Mates, in Plato's Republic, would be chosen by a "marriage number" in which the quality of the individual would be quantitatively analyzed, and persons of high numbers would be allowed to procreate with other persons of high numbers. In theory, this would lead to predictable results and the improvement of the human race. However, Plato acknowledged the failure of the "marriage number" since "gold soul" persons could still produce "bronze soul" children.

The Guardians will even have their families in common. Children will be raised in common and will not know who their real parents are. These children will also not be randomly conceived. They will be bred deliberately to produce the best offspring, as though the Guardians were a pack of hunting dogs. Even Plato realizes that such cold blooded match making might be too much for the Guardians, so he proposes that the process be kept secret from most of them. Every year, after the breeding committee, or whatever, secretly makes its choices, there is to be a kind of fertility festival. Everyone chooses names by lot, and the name they draw, or no name, is the choice of the gods for them. This is the kind of thing that Plato calls a "noble lie"; for the lottery is to be rigged by the breeding committee. Everyone will actually draw the name designated for them; and those who draw a blank were simply thought undesirable for offspring.