Dioscuri, Castor and Pollux, sons of Zeus and Leda, and brothers of Helen (of Troy) and Clytemnestra. One version of the legend says that there were two pairs of twins: Pollux and Helen (children of Zeus) and Castor and Clytemnestra (children of Tyndareus, Leda's husband). The children emerged from two eggs, which Leda laid after Zeus had coupled with her in the form of a swan. Dioscuri had many adventures, one of them is the abduction of their cousins, daughters of their uncle Leukyppos, Phoebe and Hilaera. The girls were betrothed, and Castor and Pollux were invited to the wedding feast. They liked their cousins so much that carried them away and married them themselves.
See: Peter Paul Rubens Castor and Pollux Abduct the Daughters of Leukyppos.