The primary source which confirms his parentage has not yet been identified. Vogt von St Emmeram. Graf von Cham. “De Comitibus Ratpotho et filii Udalricus et Ratpotho, Willihalm filius Ger ---“ witnessed the charter dated 17 Jul 1072 under which “--- patriarcha [aquiligiensis Syrus]” confirmed property to Michaelbeuren church after three lives “suam, suæque matris Pilihildæ comitisse nec non Mathildis uxoris fratris sui Friderici”.
The origin of [Ratpoto's first wife] Mathilde is not known. Wegener says that she was Mathilde von Lambach, daughter of Arnold [II] Graf von Lambach & his wife Reginlinde ---, but gives no basis for this speculation. 1