Family Affair

The ability to help family is common in the animal kingdom. But they don’t have a monopoly on it. Some plants have evolved to recognize their kin – and attack their enemies. We talk about the secret social lives of plants with evolutionary biologist Susan Dudley. And: learn how one father home-schooled his son—and strengthened their relationship—with three movies a week. Also: the latest campaign news, and Pete Sampras on his life in tennis.