 Urse came from an undistinguished family, and made his way on military reputation. He was probably born in about 1040, but the exact date is unknown. He was from St Jean d 'Abbetot in Normandy, where his family had lands, and where he himself was a tenant of the lords of Tancarville. Other tenants of the Tancarville lords included Robert d'Abetot and his wife Lesza, who held lands close to St Jean d 'Abbetot in the early 12th century; despite the name, it is not certain that Robert d'Abetot was related to Urse. Urse had a brother usually called Robert Despenser, sometimes known as Robert fitz Thurstin, who also became a royal official. The historian Emma Mason suggested that Urse may have been a nickname rather than a forename, perhaps given on account of his tenacious temperament. Urse's usual last name derives from his ancestral village in Normandy. His brother's usual last name of Despenser derives from his office, that of dispenser, in the royal household.
