House of Welf
Welf III was the only son of the Swabian count Welf II of Altdorf (died 1030) and Imiza, a daughter of Count Frederick of Luxembourg and niece of the later empress Cunigunde of Luxembourg. His sister Kunigunde of Altdorf (1054) married Margrave Albert Azzo II, of Milan, a member of the Italian House of Este, and became the ancestor of the House of Welf-Este of (Younger) House of Welf.