How does the author use foreshadowing in Franny and Zooey?

Zooey's acerbic back-and-forth conversation with his mother reveals the connection with his sister, and foreshadows a problem the pair will have. Franny spoke of people who have egos and are always critical. Zooey appears to be the same kind of person. He treats his mother with disrespect and talks down to her, an obvious sign of ego. More than just critical, though, Zooey appears to be mean and even borderline cruel to his mother, calling her fat and stupid. His form of communication with his mother is a combination of insults, shouts and bitter sarcasm. In short, Zooey sounds exactly like the kind of person Franny says she can't stand.