An oracle then advised Thyestes that, if he had a son with his own daughter Pelopia, that son would kill Atreus. Thyestes did so by raping Pelopia (his identity hidden from her) and the son, Aegisthus, did kill Atreus. However, when Aegisthus was first born, he was abandoned by his mother, ashamed of the origin of her son. A shepherd found the infant Aegisthus and gave him to Atreus, who raised him as his own son. Only as he entered adulthood did Thyestes reveal the truth to Aegisthus, that he was both father and grandfather to the boy and that Atreus was his uncle. Aegisthus then killed Atreus.