Hi William,
Your essay covers an interesting topic. Genetic technologies will certainly open up many new ways to treat and cure disease! The suffering caused by chronic illness is systematically underestimated by many people because often it is partially out of sight!
However, while one would hope parents would be a little more responsible with their own children, I can't help but look, in my less optimistic moments, at some of the breeding of pet animals (also originally concerned with health improvement), some of which results in chronic painful illness in the animal, and wonder if the fashionable choices of thoughtless parents might result in poor outcomes of their own. After all, high rates of unplanned pregnancies seem to suggest not all parents are very good at planning for the future.
I also wonder if parents uniformly choose their characteristics from the big 5 psychology traits, will there be some broader social outcomes? For example, parents might prefer extroverts, but to lose introverts from our society would be an immense loss with consequences I'd be hesitant to try to predict, even having studied quite a bit of social science myself!
Interesting topic in any case! Thanks!