Depends. Do I have a problem with people intentionally mating in order to produce children with desired traits (like Heinlein's Howard Family)? Nope, I have no problem with that, because it is a process that requires multi-generational "patience" and is no different than selective breeding of other animals in order to get desired results. Do I have a problem with those who are not patient enough to allow genetics to "do its thing" over multiple generations and feel that "killing off those with undesirable traits" or "preventing those with undesirable traits from reproducing" is an acceptable practice? Yes, I do. I see the former as being a matter of free-will and a conscious choice by consenting individuals and the latter as a "cover story" and excuse for prejudice, racism, and genocide.