Aegisthus in Wikipedia

In Greek mythology, Aegisthus (Ancient Greek: Αἴγισθος ; also transliterated as Aegisthos) was the son of Thyestes and of his daughter, Pelopia. Thyestes felt he had been deprived of the Mycenean throne unfairly by his brother, Atreus. The two battled back and forth several times. In addition, Thyestes had an affair with Atreus' wife, Aerope. In revenge, Atreus killed Thyestes' sons and served them to him unknowingly. After eating his own sons' corpses, Thyestes asked an oracle how best to gain revenge. The advice was to father a son with his own daughter, Pelopia, and that son would kill Atreus. When Aegisthus was born, his mother was ashamed of her incestuous act. She abandoned him and he was raised by shepherds and suckled by a goat, whence his name Aegisthus (from αίξ).[1][2] Atreus, not knowing the baby's origin, took Aegisthus in and raised him as his own son...

Link: https://en.wikipedia.org/wiki/Aegisthus