She was born at St. Francis Hospital in Blue Island, Illinois. Bertrand was brought up in the nearby small town of Riverdale. Her parents were Lois June (née Gouwens; 1928–1973) and Rolland F. Bertrand (1923–1985). She had two younger siblings: a sister, Debbie, and a brother, Raleigh. Her father was of French Canadian ancestry, while her mother was of Dutch and German ancestry. She also claimed to be of Iroquois ancestry, although her only known Native American ancestor was a Huron woman born in 1649. According to her daughter, actress Angelina Jolie, Bertrand was often wrongly identified as a French actress, with Jolie saying, "My mom is as far from French Parisian as you can get. She grew up in a bowling alley that my grandparents owned." In 1965, Bertrand's family moved from the Chicago area to Beverly Hills, California. She attended Beverly Hills High School from second year through graduation.