SEASON 1, EPISODE 101 | AIRED ON 08/28/12

Moment #22: Mackenzie Phillips' Shocking Family Secret

Of all the confessions in the Oprah Show vault, TV Guide Magazine picked this as the ultimate shocker. On September 23, 2009, former One Day at a Time star Mackenzie Phillips appeared on The Oprah Show to reveal a family secret she'd kept for years. She told Oprah that she'd carried on a sexual relationship with her father, John Phillips, the founder of the Mamas & the Papas, for approximately 10 years.