Clytemnestra produced four offspring from two eggs: Castor and Clytemnestra from one egg, and Helen and Polydeuces (Pollux) from the other. Therefore, Castor and Clytemnestra were fathered by Tyndareus, whereas Helen and Polydeuces were fathered by Zeus. Agamemnon and his brother Menelaus were in exile at the home of Tyndareus; in due time Agamemnon married Clytemnestra and Menelaus married Helen. In a late variation, Euripides's "Iphigenia at Aulis", Clytemnestra's first husband was Tantalus, King of Pisa; Agamemnon killed him and Clytemnestra's infant son, then made Clytemnestra his wife. In another version, her first husband was King of Lydia. The kings of
Greek mythology was their sexual companion, to every important god except Ares and to many legendary figures. Previously existing myths, such as those of Achilles and Patroclus, also then were cast in a pederastic light. Alexandrian poets at first, then more generally literary mythographers in the early Roman Empire, often re-adapted stories of Greek mythological characters in this fashion. The achievement of epic poetry was to create story-cycles and, as a result, to develop a new sense of mythological chronology. Thus Greek mythology unfolds as a phase in the development of the world and of humans. While self-contradictions in these stories make