It's an intriguing idea that seems to be associated with Soviet-era training and the mechanization of human beings, coerced into insect-like castes, as in Brave New World, and the lovely short-story Unaccompanied Sonata http://en.wikipedia.org/wiki/Unaccompanied_Sonata (or Ender's Game itself for that matter.)

I know you don't mean coercion, but simply informed choice; but I think the rebuttal is the same: our theories are not adequate to predict such things, even if we had all the information; especially when factors like 10,000 hours of practice and motivation seem so important. At best, they can suggest a probability distribution. Or: you don't know til you try.

I guess some specifics could be useful, like a probability distribution of expected height for a baby, for his/her potential as a basketball player. However, at the very young age where genome knowledge is most effective (by revealing as yet unexpressed traits). the baby is not able to make a choice. So it would effectively be Soviet-era training.