Background
He was son and heir of John I, Count of Ponthieu (d 1191) by his third wife Beatrice de Street Policy His father Jean I, Count of Ponthieu (d 1191 was the son of Guy II, Count of Ponthieu (who died on the Second Crusade 1147) and grandson of William III of Ponthieu, also frequently called William III Talvas, and who represented the senior line of the lords of Montgomery, once trusted vassals and allies of William the Conqueror.