If defective persona is genetic, how can one be sure that they do not have a defective persona?
How can we know that the concept of eugenics itself doesn't arise from a defective need to control things? How do you know that you don't have it wrong if your sense of wrong is somehow deterministic?
On the other hand though, I think humans are animals and will just do what they do for good or ill. Either eugenics will be or not be. And actually that in itself would tie into genetic determinism.
Also I'd like to say that nature doesn't get anything wrong. We only perceive things as such.
Also note that if we didn't have an industrialized society, these people would probably die or be killed off, either from not having the skills to survive or from being killed in self defense or territorial contest.
Intervention is what gives them a foothold to propagate in the first place.