She was born in the suburbs of Melbourne in the family of Robert and June. Her father was from Texas and served as a naval officer. After marrying Jun, a teacher at a Melbourne school, he emigrated to Australia and went into the advertising business. When she was only ten years old, he died of a heart attack. Raising her three older brothers, Bob (now a computer engineer) and younger sister Genevieve (now a theater costume designer) lay on the shoulders of his mother.

She attended the Ivanhoe East Primary School in Melbourne, then went to the Ivanhoe Girls' Grammar School, and then to the Melbourne Women's Methodist College. There she made her first appearance on stage - she took part in several productions of the school theater, including in the Odyssey of Renyon Jones. She then continued her studies at the University of Melbourne, where she studied art and economics. But soon left the university and went to travel around England. When the visa expired, Kate, practically without money, and also without concrete plans, went to Egypt, where at the hotel she met a tenant who offered her to star in an Egyptian boxing film. Since the girl needed money, she agreed. This random role was the beginning of her creative path.