Mackenzie's Sis -- Dad Never Made a Move on Me

Mackenzie Phillips' half-sister claims their father never made sexual advances towards her -- even though Mack supposedly had an incestuous 10-year relationship with the guy.

Chynna Phillips: Click to watch
Chynna defended her sister today on Oprah -- where she said she absolutely believes the "hideous" allegations Mackenzie made about their dad, Mamas and the Papas singer John Phillips.