Louise was the daughter of Guillaume de Penancoët, Seigneur de Kérouaille (d.
Louise had a sister, Henriette Mauricette de Penancoët de Kérouaille, who married firstly in 1674 Philip Herbert, 7th Earl of Pembroke and secondly in 1685 Jean-Timoléon Gouffier, Marquis de Thais [REF].