I don't see anything wrong with parents picking out their child's genetics. Since parents know what they lack in their life, they can correct that in their kids life. It would be benefited to child as well because they would possesses good genes that would make them who they are in the end. Only question is that if its possible.
I would say no because, there is only one of you an if you go an choose your child's gentics then there could be many people like that! While there will never be another you even if your a twin you make you your twin isn't gonna be the same person you are.
Nobody should be able to modify their own genes. It should be part of natural selection. Genetic modifications is largely unethical, and it opens up the door to plentiful nightmare scenarios. The science is getting much closer, and such practices will need an ongoing level of scrutiny by ethicists and scientists.