18. This Dynasty Got Started on a Tradition of Inter-Family Relations Early On
Ptolemy I, the first ruler and founder of the Ptolemaic Dynasty, was a capable general. He had learned from and served under one of history’s greatest military geniuses, Alexander the Great. His son and successor, Ptolemy II (308 – 246 BC), did not inherit his father’s military chops. He opted instead for peaceful and cultural pursuits, patronized scientific research, and expanded the Great Library of Alexandria. In his reign, the Ptolemaic court in Alexandria reached a height of splendor that would not be seen again.
Another distinction of the second Ptolemy is that he was nicknamed Phialdelphos (“lover of his sister”). It was because he took sibling affection to lengths hitherto alien to Greeks and Macedonians, but common among Egyptian royals. He had initially been married to Arsinoe, the daughter of King Lysimachus of Thrace – who was also married to Ptolemy II’s sister Arsinoe II, which made Lysimachus his father-in-law as well as brother-in-law. After Lysimachus’ demise, Ptolemy II got rid of the Thracian king’s daughter, Arsinoe, and married his own sister, the widowed Arsinoe II, and kicked off a tradition of Ptolemaic inbreeding that lasted for centuries, until the dynasty finally fell.