“Mackenzie went on to say that her incestuous relationship with her father had become consensual and the two engaged in sexual activity for years despite being directly related and both being married. Mackenzie eventually became a member of the New Mamas and the Papas, and toured with John during the early 1980s.
John apparently wanted to run away with her to a country where their relationship wouldn’t be looked down upon. But the incestuous relationship eventually ended when Mackenzie became pregnant and was unsure of who had fathered the child. John paid for her to have an abortion, but it was from that point, Mackenzie said, that “I never let him touch me again.”
The musical architect of The Mamas and the Papas, John Phillips, had a short and sordid life that involved drama, drugs, and incest.
Source: John Phillips: The Sordid Life of ‘The Mamas and the Papas’ Co-Founder