Leda was wife to Tyndareus of Sparta and mother to Helen, Clytemnestera, Castor and Pollux. Helen was the daughter of Zeus, he approached Leda in the form of a swan. (Zeus seduced Alcheme in that form as well. She was mother of Hercules and his twin brother Iphicles.) Some say that the Dioscuri (Castor and Pollux) were the sons of Tyndareus, and others say that Pollux was the son of Zeus and Castor the son of Tyndareus. It seems after reading much mythology that Zeus wanted to people olympus with his offspring.