Kerr was born in Sydney and raised in the small town of Gunnedah, New South Wales. She is the daughter of Therese and John Kerr. She has a brother, Matthew, who is two years younger. In an interview, Kerr stated she is of English, French, and Scottish descent. During her childhood, Kerr "raced motorbikes and rode horses on her grandmother's farm." She describes her early life in the Australian countryside as "very grounding ... there wasn't any pretentiousness and no one really cared what you were wearing. You could just be you."