Kelly was born in Los Angeles. She is the only child of former Aerosmith guitarist Rick Dufay and Maureen Dumont Kelly, an exotic dancer. Her parents split up when she was young, and she was raised by her mother. Her paternal grandfather was actor and investment advisor Richard Ney. Kelly and her mother often moved to different communities, before settling in Albuquerque, New Mexico by the time Kelly was in junior high school. She has French and Irish ancestry.