Frank Kogan

Post nuclear war, the area of "Labrador" has developed to level of early 19th-century agrarian, surrounded by badlands and beyond that wastelands, though badlands are slowly becoming more habitable and civilization has started encroaching in this frontier area; the badlands populated by outcasts and mutants, who are being pushed back. The two pieces of written matter that survived nuclear holocaust were Bible and a book describing the correct human form. Protaganists Fundamentalist type religion dominates, the theology including the idea that the devil attempts to imitate animals and plants and humans, but not being the lord God himself always screws up, so mutations are signs that the creature was created by the Devil. Some politics in deciding that large horses and special crops owned by influential landowners are fine rather than mutant. Main character is boy who befriends girl with six toes. She is eventually discovered and banished. He also in the evening goes to his backyard and talks to his gorgeous cousin. After a while we realize that she is not actually there with him in the backyard, that they are communicating telepathically. Sympathetic uncle figures this out. Boy and cousin become teens and fall in love. Boy has little sister whose telepathic powers outshout everyone else's. You can figure lots of plot from there.