Maria Stella Bicker Correia Ribeiro Piteira Santos was the daughter of Maria do Carmo Bicker from the Algarve and of a military doctor who participated in the 5 October 1910 revolution that overthrew the Portuguese monarchy. She was born on 1 June 1917, when her father was in Flanders, during Portugal's participation in World War I. Coming from a middle-class background, she initially studied at home, where one of her teachers was a young German woman. After her teacher's return to Germany, she spent three years at the German School in Lisbon in order to avoid losing her knowledge of German, and then studied at the "Colégio das Doroteias" in Sintra, near the Portuguese capital of Lisbon, where she received a conventional Portuguese religious education. However, she only completed her schooling after marrying Inácio Fiadeiro at the age of 17 and having two children. Fiadeiro was a communist and four years her senior.