If I were able to choose all genetic traits of my future children I would want them to have the best genetics possible. When it comes to working out, genes are what determine your limits of you're full body growth, so I would have these genes modified to where they can perform their best and be naturally gifted with great genes in order to obtain maximum body mass. I would also like them be to genetically gifted to where they are natural athletes. Being the best in any sport they desire would be best for my children but of course they will still train hard. The only thing wrong with designer babies would probably be religion. As a child of god, you are brought to this world as he sees best and many people follow this philosophy. This may cause a major debate on the topic of genetic modification. Maybe this could be good to a certain extent though. Rid of genes that cause hereditary diseases could be a cure to many diseases or the radification of them. As long as this is kept to a homeostasis, I do not see the problem with minor modifications.