The Saint-Aubin genealogies, evidently composed during the reign of Fulk IV, not only give the name of the father of Fulk IV and his brother Geoffroy III le Barbu, but provide the maternal ancestry of their father as Beatirx, daughter of Albericus, son of Letaldus ["Letaldus comes Vesconsiosis (et Umbertus comes Matisconiensis fratres fuerunt ...); ex Letaldo Albericus natus est; ex Alberico Beatrix; ex Beatrice Gosfridus comes de Castello Landonensi. Ex Gaufrido Gaufridus et Fulco presens."]. There are some authors who have proposed mother's for Béatrix other than Aubry's wife Ermentrude, the daughter of Renaud, Count of Roucy. While there is not enough evidence to refute those claims, it seems less likely due to the need to invent heretofore unknown persons. The claims tend to be based on the passing of the succession of Count of Gâtinais onto her son. It has been clearly shown that this title was passed from his half-brother Aubry, so there is no need to invent new characters to fit an alternate succession.