If he [Skinner] is right (not that I am at all certain that he is), or even right about the first bit, then Ridley's theory is impossible

Ridley is basically saying that Skinner is wrong. Each chapter begins with a quote and the one for this chapter is "The tabula of human nature was never rasa." -W.D. Hamilton. Ridley is approaching the subject from an almost purely genetic viewpoint, using the most up-to-date (well, 2000 anyway) information from the Human Genome Project. I don't think he really thinks that literacy will become innate (he doesn't elaborate on the idea), but he's just putting it out there for consideration.

He gives an example of the language instinct:
". . . the most startling evidence for a language instinct comes from a series of natural experiments in which children imposed grammatical rules upon languages that lacked them. In the most famous case, studied by Derek Bickerton, a group of foregin labourers brought together on Hawaii in the nineteenth century developed a pidgin language -- a mixture of words and phrases whereby they could communicate with each other. Like most such pidgins, the language lacked consistent grammatical rules and remained both laboriously complex in the way it had to express things and relatively simple in what it could express. But all that changed when for the first time a generation of children learnt the language in their youth. The pidgin acquired rules of inflection, word order and grammar that made it a far more efficient and effective language -- a creole. in short, as Bickerton concluded, pidgins become creoles only after they are learnt by a generation of children, who bring instinct to bear on their transformation."