Adulthood Rites by Octavia E. Butler
In the future, nuclear war has destroyed nearly all humankind. An alien race intervenes, saving the small group of survivors from certain death. But their salvation comes at a cost.
The Oankali are able to read and mutate genetic code, and they use these skills for their own survival, interbreeding with new species to constantly adapt and evolve. They value the intelligence they see in humankind but also know that the species -- rigidly bound to destructive social hierarchies -- is destined for failure. They are determined that the only way forward is for the two races to produce a new hybrid species -- and they will not tolerate rebellion.
Akin looks like an ordinary human child. But as the first true human-alien hybrid, he is born understanding language, then starts to form sentences at two months old. He can see at a molecular level and kill with a touch. More powerful than any human or Oankali, he will be the architect of both races' future. But before he can carry this new species into the stars, Akin must reconcile with his own heritage in a world already torn in two.