Arnold Rothstein was born into a comfortable life in Manhattan, the son of an affluent Ashkenazi Jewish businessman, Abraham Rothstein, and his wife, Esther. His father was a man of upright character, who had acquired the nickname "Abe the Just".[4] Arnold was highly skilled at mathematics, but was otherwise uninterested in school.[4] His older brother, on the other hand, studied to become a rabbi.[5]