He was a younger maternal half-brother of Marie de Champagne and Alix of France. He was a younger brother of William IX, Count of Poitiers, Henry the Young King, Matilda, Duchess of Saxony and Richard I of England. He was also an older brother of Queen Eleanor of Castile, Queen Joan of Sicily and John of England. He was also the half-brother of his father's illegitimate sons Geoffrey, archbishop of York, William Longespée, 3rd Earl of Salisbury and Morgan, provost of Beverley. As a participant in so many rebellions against his father, Geoffrey acquired a reputation for treachery. Gerald of Wales said the following of him: He has more aloes than honey in him; his tongue is smoother than oil; his sweet and persuasive eloquence has enabled him to dissolve the firmest alliances and his powers of language to throw two kingdoms into confusion. Geoffrey also was known to attack monasteries and churches in order to raise funds for his campaigns. This lack of reverence for religion earned him the displeasure of the Church and also of the majority of chroniclers who were to write the definitive accounts of his life. Geoffrey was buried at Notre Dame Cathedral Costain, Thomas B. The Conquering Family, 1962 Everard, Judith. Charters of Duchess Constance of Brittany and her Family, 1171- 1221, 1999
Everard, Judith. Brittany and the Angevins: Province and Empire, 1158 -1203, 2000