Agatha Miller was born on 15 September 1890 in Torquay, Devon.
Her parents were wealthy settlers from the United States. She was the youngest daughter in the family of the Millers. The family of the Millers had two other children: Margaret Freres (1879-1950) and the son of Louis Montagne "Monty" (1880-1929). Agatha received a good education at home, in particular, the music, and only stage fright prevented her from becoming a musician.
During the First World War, Agatha worked as a nurse in the hospital, she liked the profession, and she spoke of her as' one of the most rewarding professions, which can engage people "[6]. She also worked as a pharmacist in a pharmacy, which subsequently delayed the imprint on her work: 83 crimes in her works have been committed by poisoning .
Агата Миллер родилась 15 сентября 1890 года в городе Торки, графства Девон.
Её родители были состоятельными переселенцами из Соединённых Штатов. Она была младшей дочерью в семье Миллеров. В семье Миллеров было ещё двое детей: Маргарет Фрэри (1879—1950) и сын Луис Монтан «Монти» (1880—1929). Агата получила хорошее домашнее образование, в частности, музыкальное, и только страх перед сценой помешал ей стать музыкантом.