When Miriam was young, her father abandoned the family and went to Europe. Until that point the family had lived comfortably in Washington Heights, but Julian Cooper kept the inheritance, leaving the family destitute. They moved to Little Italy, which Cooper despised. Cooper had a troubled relationship with her mother, whom Cooper loved but felt was cold to her. Once during her childhood her mother told her she hated Miriam for looking like her (Miriam's) father. Her mother remarried in 1914.