They kinda do this already if you consider optimizing parental nutrition and fitness prior to conception, ensuring ideal nutrient content and minimal natal toxins for the baby, and more enrichment classes and such than you can shake a stick at, starting in early infancy as making changes to the babies 'potential.' Considering how much effect epigenetics has on your final phenotypic expression I would say that this is already occurring today, just in a less targeted manner. It's the difference between selectively breeding shorter and shorter wheat crops, and just editing a gene to make the plant less responsive to the hormone that makes it grow taller.Rich parents will be able to design smarter kids,
Although they can contribute to epigenetic changes, which can also be hereditary (as far as I understand, anyway, I'm a layman with a liberal arts background).