Philopappos’ parents were distantly related. The paternal grandmother of Claudia Capitolina was Greek Princess Aka II of Commagene, who was a great granddaughter of King Antiochus I Theos of Commagene, while his father was the first-born son of King Antiochus IV of Commagene and his wife Queen Julia Iotapa of Commagene. Antiochus IV and Iotapa were direct descendants of Antiochus I Theos.