Because the Ptolemaic kings adopted the Egyptian custom of marrying their sisters, many of the kings ruled jointly with their spouses, who were also of the royal house.
Karena raja-raja Ptolemaios mengadopsi adat Mesir dengan menikahi saudari mereka sendiri, maka banyak raja yang berkuasa berdua bersama pasangan mereka, yang masih berasal dari keluarga kerajaan.