The trees in the street are old trees used to living with people,
Family trees that remember your grandfather’s name.
—Stephen Vincent Benét, John Brown’s Body
Initially I toyed with the idea of making the previous problem (with its suggestive title) the last problem in the book. But with this problem we’ll end with what comes after (usually) all the dating—babies! But before I formulate the central problem to be posed here, let me start by discussing what might seem to be a totally off-the-wall ...