Johnson was born in Camarillo, California, the youngest daughter of Nancy Spruiell Johnson, an independent film Producer, and Clifford Johnson, the captain of an exploration ship. Her father died in July 2000 from Hepatitis C and cancer. She is of Norwegian, Swedish, Danish, Irish, Scottish, and Native American descent. When she was nine days old, her father got a new job and the family moved to Franklin, Michigan. Johnson graduated from high school at 15.