Consensual incest is a topic that's rarely—if ever—discussed. Mackenzie says she can't explain why this forbidden affair went on for so long, but she believes drugs and alcohol were partly to blame.
"My father was not a bad man. He was kind of a testament to what drugs and alcohol—in huge quantities—can do to a person's priorities. Their motives," she says. "I don't hate him. I understand that he was a very tortured man, and he sort of passed that torture down to me."
That wasn't the only thing Mackenzie shared with her father. As a teen, Mackenzie says her father, the man she idolized, taught her how to shoot up cocaine, and they often got high together. "What you've been taught is what you know, and that was kind of like it for me," she says. "I didn't have very good role models."
After she landed the starring role on One Day at a Time alongside actress Valerie Bertinelli, Mackenzie's life began to revolve around drugs. She freebased cocaine, popped pills and dropped acid in the glare of the public spotlight. Then, two years after Mackenzie's first arrest, she was fired from One Day at a Time.