Francis Xavier was born in the royal castle of Xavier, in the Kingdom of Navarre, on 7 April 1506 according to a family register. He was the youngest son of Juan de Jasso y Atondo, seneschal of Xavier castle, who belonged to a prosperous farming family and had acquired a doctorate in law at the University of Bologna. Basque was his mother tongue. Juan later became a privy counsellor and finance minister to King John III of Navarre (Jean d'Albret). Francis's mother was Doña María de Azpilcueta y Aznárez, sole heiress of two noble Navarrese families. He was related through her to the great theologian and philosopher Martín de Azpilcueta.