There are two pairs of twins in Genesis, but most of us only notice the first. Jacob and Esau get the headlines: the smooth wheeler-dealer who becomes the father of the Israelites and his hairy, oafish twin who gets tricked out of his birthright for a bowl of soup. By contrast, Perez and Zerah (Gen. 38) fly under the radar. They don’t appear in kids’ Bibles, or even sermons. Yet in many ways, they summarize the biblical story more crisply than any other siblings in Scripture.