@TheMariquis, you do know heil will then say we need to do selective breeding programs with humans. He has often stated in the past that anybody with genetic defects or disadvantages should be aborted.
But you are not exactly picking the breed, you are picking the group that has the highest probability of having the better individuals. With limited information you have to make a generalization. But that generalization is still based on the individuals ability just translated as an average.
If the all of the individuals of a certain breed ended up being bad at the job, (for instance continued breeding for the trait desired ended causing genetic problems) the breed would lose its status of being good at the job.