 John was the second surviving son of John II, Duke of Brittany, and his wife Beatrice, who together had three sons and three daughters who survived to adulthood. Beatrice was the daughter of Henry III of England, which made John the nephew of Henry's son and heir Edward I. His father held the title of Earl of Richmond, but was little involved in English political affairs. John was raised at the English court together with Edward I's son Henry, who died in 1274. He participated in tournaments in his youth. but never distinguished himself in his early roles as a soldier.
