Yes, there’s going to be some inherent conflict between these elements. The first rule will have to be implemented by some external system. Not forcing changes on parents, but forbidding changes that can’t be objectively shown to be beneficial to the individual. Like some kind of family court, that evaluates the reasons for the change, and can disallow things like, “I want my kid to be 6’10” so he can get in the NBA!" The goal would be to maximize the kid’s potential choices in life, and being genetically tunneled towards one specific job reduces such choices.