 Lettice's maternal great-grandmother was Mary Boleyn, elder sister of Anne Boleyn, the second queen consort of King Henry VIII of England, who had been the lover of Mary prior to his courtship of Anne and possibly the biological father of her daughter Catherine.Her paternal grandparents were Gerald FitzGerald, 11th Earl of Kildare and Mabel Browne.One of her aunts, and after whom she was likely named, was Lettice Knollys, the celebrated rival of Queen Elizabeth I, who was also a distant cousin of the Knollys family.