Commenters are often surprised that, although I fully acknowledge dysgenic changes and over-population, I am against eugenics.
The reason is quite simple: I am a Christian, and eugenics is a secular, economic doctrine.
Eugenics gives primacy to secular economic priorities such as power, prosperity and efficiency.
And, like all secular ideologies, eugenics comes-up against the problem of motivation - how can people be motivated to make difficult changes and behave in the way eugenicists want them to behave?
We know, from experience, that the only secular motivations strong enough to drive policy are inevitably negative (sinful) incentives such as pride, selfishness, hedonism and hatred.
In practice I have no doubt at all, that any actual and implemented eugenic policy would be driven by negative motivations - and would therefore be evil in effect (whatever its supposed intentions).
There is no shortcut to good policies and good government - good policies and good government lie on the other side of religious conversion - in particular, on the other side of repentance where dwell honesty, humility, love and the desire to do divine work.
Any good policy (good overall and in the long term) must be motivated by love and humility towards God's purposes - and only after that attitude is 'in place' the right and proper and best (or, more often, least-worst) actions may become clear, along with the positive motivations necessary to their accomplishment.