A short story about the consequences of normalized post-birth genetic alteration: http://compellingsciencefiction.com/stories/thelittlegods.ht...
A short description of the pre-birth and post-birth conditioning present in Aldous Huxley's famous Brave New World: https://en.wikipedia.org/wiki/Brave_New_World#Fordism_and_so...
The Last Book In The Universe takes a different approach to the issue. A cataclysmic event called The Big Shake destroys society, and only a small group of surviving scientists hidden underground were able to genetically modify their offspring to be superior to the rest of the world. This creates an immensely divisive class system, and the genetically altered humans live and govern separately from the rest of the planet.
This will not be an easy problem to solve, and there is no telling what the future effects will be. But it seems precise genetic alteration is the inevitable holy grail, doesn't it?
This is the tip of the iceberg. Once we have a million genomes tagged with cognitive measures, a huge swath of politically-incorrect but factually true descriptive statements will be confirmed. We need to work now to avoid confusing the descriptive with the normative and be willing to consider technological fixes for unfair distributions of economically valuable allies, such as embryo selection and direct genetic modification. Our society is so in denial of biological realities, this may not happen in time. But there will be competitive pressure from Asian (and perhaps Islamic) societies that do not share our tabbos.