Laius and Jocasta had been warned by an oracle that their son would grow up to kill his father, so Laius had the newborn baby's ankles pierced and tied together before leaving him on a mountainside to die. However, the baby was found and rescued by a shepherd, who took him to Polybus and Merope, who were unable to have children of their own.
Oedipus grew up believing Polybus and Merope to be his parents. However, as an adult, he learned of the prophecy and Oedipus' true parentage, and he went on to fulfill the prophecy by killing Laius and marrying Jocasta without knowing their relationship.