The female button beetle mates with her son and then eats him. Some male mites copulate with their sisters inside their mother's womb. So when is incest acceptable? Sea hares engage in lengthy orgies-they are hermphrodites, so they can play the male role and the female role both at the same time. When is it a good idea to be a hermaphrodite? Meanwhile, the bdelloid rotifer has not had sex for millions of generations. Why not? And why don't the rest of us follow her example? Find out...

This episode features several interviews, including with Dan Fessler, an anthropologist at UCLA, and with Janet Leonard, a banana slug expert at UC Santa Cruz.

And it features songs such as The Trouble with Sex, and Strangely Familiar.