Hess, the oldest of three children, was born on 26 April 1894 in Alexandria, Egypt, into the ethnic German family of Fritz Hess, a prosperous merchant from Bavaria, and Clara Hess (née Münch). His brother, Alfred, was born in 1897 and his sister, Margarete, was born in 1908. The family lived in a villa on the Egyptian coast near Alexandria, and visited Germany often from 1900, staying at their summer home in Reicholdsgrün (now part of Kirchenlamitz) in the Fichtel Mountains. Hess attended a German language Protestant school in Alexandria from 1900 to 1908, when he was sent back to Germany to study at a boarding school in Bad Godesberg. He demonstrated aptitudes for science and mathematics, but his father wished him to join the family Business, Hess & Co., so he sent him in 1911 to study at the École supérieure de commerce in Neuchâtel, Switzerland. After a year there, Hess took an apprenticeship at a trading company in Hamburg.