Who decides how children should be brought up? These kinds of conflicts will sort themselves out like they've always be done. With loud argumentation and crockery projectiles. I'm sure there will be trends just like we have with clothes today. I'm sure there's nothing to worry about.
The most important thing to keep in mind is that this will happen, whether we want it or not. If not legally, then illegally. Parents strong wishes to have a healthy child just like they've dreamed of, will trump anything any government or moral opinion could say anything about.
He he. You're still mixing up the subject of eugenics with Nazi practices. This can all be put down as paranoid ramblings that will never happen...again. Because nobody would want it. Democracy is good that way.