Joan was thus doubly descended from Henry II and Eleanor of Aquitaine.
[2] Joan's mother was a half-sister of Edward II's favorite, Hugh le Despenser the Younger, through the remarriage of Maud's mother, Isabella de Beauchamp, to Hugh le Despenser, 1st Earl of Winchester.
Joan had one brother, Henry of Grosmont, 1st Duke of Lancaster, and five sisters, Blanche, Baroness Wake of Liddell, Isabel, Abbess of Amesbury, Maud, Countess of Ulster, Eleanor, Countess of Arundel and Warenne, and Mary, Baroness Percy.
[3] Joan's niece, Elizabeth de Burgh, Countess of Ulster, married Lionel of Antwerp, Duke of Clarence, the second surviving son of Edward III and Philippa of Hainault, a marriage that would create a line of descent to strengthen the Yorkist claim to the throne in the Wars of the Roses.
[4] Another niece, Blanche of Lancaster, married the third surviving son of Edward III, John of Gaunt, and became the mother of the first Lancastrian king of England, Henry IV.