Mary Benedict Cushing was the eldest daughter of Harvey Williams Cushing (1869-1939) and Katharine Stone Crowell.
Her two sisters, also prominent socialites, were Betsey Maria Cushing (1908-1998), who was married to James Roosevelt II and later to John Hay Whitney, and Barbara Cushing (1915-1978),[REF] who married Stanley Grafton Mortimer, Jr. and later William S. Paley [REF].