[2] His younger brothers were Paul (1886–1946), Friedrich (1890–1940) and Hans (1895–1968), who later served as president of the family's investment firm, United Continental Corporation.

[5] The Petschek family founded various international mining and chemical enterprises in Prague,[6] Czechoslovakia (now Czech Republic).

Their concern controlled also 30% of the German and, in total, almost 50% of the European brown coal mining industry in the years after World War I.

His cousin Walter (Julius' son) and Otto's brother Hans Petschek ran the company until 1938 when they moved to New York as a consequence of the Munich Agreement.

[15] In December 1966, Otto's granddaughter, Angela Conway Petschek, was married to Alain Patrick Maze-Sencier of Paris and New York, the Count de Brouville.