Known by the English form of her name, Mary (her maternal grandfather's second wife was English), she was the third child of Albin von Vetsera, a diplomat in foreign service at the Austrian court, and his much younger wife, Hélène (also known as Eleni) , a member of a wealthy Greek noble family from the island of Chios, then part of the Ottoman Empire. Albin, who was made a baron in 1870 by the Emperor Franz Joseph, was 22 years older than his young and socially ambitious wife. Mary had three siblings: Johanna (known as Hannah), Ladislaus, and Franz Albin. Both of Hélène's sisters had married counts and Mary and her sister were expected to raise the family's social status by continuing the tradition of marrying into families of importance.