"I think it affected her forever," Peterson's mother, Sylvia, said on a recent episode of The Doctors.
Peterson's father, James, added: "She became so defensive, less trusting. Some of the sparkle was gone."
The assault occurred at the height of Peterson's acting career, as she rose to fame playing Cindy Mancini in Can't Buy Me Love, opposite Patrick Dempsey. She refused to press charges. "She just felt so ashamed. She didn't want people to know," according to her mother.
In the 1990s and 2000s, Peterson struggled with addiction and had a number of legal issues. The actress, who suffered from bipolar disorder, was found dead at her home in Colorado in July. The cause of death was determined to be an accidental morphine overdose.
Watch the Petersons' interview on The Doctors here: