5. Mackenzie Phillips
Most Infamous Moment: In 2009, Phillips confessed to carrying on a 10-year consensual sexual relationship with her father John Phillips, of the Mamas and the Papas, after he raped her in a hotel room when she was 19 and on a drug binge.
During her appearance on The Oprah Winfrey Show, Phillips read an excerpt from her book, High on Arrival, stating, "I woke up that night from a blackout to find myself having sex with my own father." The confession ultimately alienated her from the family, which includes half-sister actress Bijou Phillips and Chynna Phillips.
But that wasn't her first scandalous moment. In the 1970s, while being a teen starlet in the sitcom One Day at a Time, Phillips was arrested for public drunkenness and cocaine, which eventually got her fired from the show in 1980. Despite several relapses and rehab treatments throughout the 80s and 90s, Phillips, who claimed her father begain injecting heroin in her as a pre-teen, was arrested at Los Angeles International Airport for possession of cocaine and heroin.