Sotiriou was born in Aydin, in western Anatolia and at that time part of the Ottoman Empire, as the daughter of Evangelos Pappas and Marianthi Papadopoulou, in a wealthy and polyglot bourgeois Rûm family who lived in a stately home. Her childhood, Sotiriou said, appeared to her as an "endless fairy tale". She had two older and two younger siblings. After her father, an entrepreneur, went bankrupt and her family became poor, Dido, who at that time was about eight years old, was sent to her wealthy uncle and his wife in Athens, where later she was educated. Sotiriou later described this separation from her family as "my first experience as a refugee". In 1919 the family moved to Smyrna (now Izmir), at that time occupied by Greece, but in 1922 Turkey repulsed the Greek invasion of Asia Minor (Greek-Turkish War), and Sotiriou's family had to leave Smyrna because of the Greek-Turkish population exchange.