Although the medieval and twelfth century sources agree that the father of Fulk IV and Geoffroy III le Barbu was a count of Gâtinais, they disagree on their father's name, some claiming Aubry (Albericus) and others Geoffroy (Gaufridus, Gosfredus, etc.). Contemporary sources, however, clearly prove that their father's name was Geoffroy. Fulk IV names his parents as Gauffridus and Ermengardis in a donation of 1074×6. Additionally, The Historiæ Andegavensis, supposedly written by Fulk IV, names his parents as Goffridi and Ermengardis ["Ego Fulco Comes Andegavensis, qui filius fui Goffridi de Castro Landono & Ermengardis filiae Fulconis Comitis Andegavensis, & nepos Gofridi Martelli, qui fuit filius ejusdem avi mei Fulconis & frater matris meae, cum tenuissem Consulatum Andegavinum vifinti octo annis ..."]. 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."]. Geoffroy III le Barbu, in a charter of 1060×8 gave a donation for the soul of his uncle and predecessor Geoffroy and his father Geoffroy ["Ipsi vero constitutum habent pro isto beneficio annis singulis facere anniversarium patris mei Gaufridi quod est II kalendas maii, non minus diligenter quam abbatum suorum anniversaria"].