Marni was married to Dr. Lajos "Fritz" Frederick Fenster between 1971-75.
In 2006, Marni gave a masterclass at Cornish College of the Arts.
Marni has been married to Albert Block since 1983.
Marni toured with Liberace and Victor Borge.
Marni took up violin at the age of 4.
Marni dubbed Deborah Kerr's singing voice in the film The King And I.
Marni was married to composer Ernest Gold, but they divorced in 1969.
Marni has a son named Andrew and two daughters named Melani and Martha.
Marni: With dubbing, you have to feel the people you're singing for are your friends. They have to share themselves with you. Once they realize you're like a sponge and aren't going to take over their performance, it's fine. The important thing is to sound as the actress would sound if she were doing the actual singing.
Marni: [on being a dubbing artist] You'd think they would have looked first and foremost for singing talent before casting those movies.
Marni: [on dubbing Natalie Wood's voice in West Side Story] I knew that I would never be cast physically in the role of Maria. In the picture they wanted Maria to sound like a sixteen year old and they kept trying out Natalie's voice. Natalie was perfectly musical, but I had the feeling that it was only gradually when they started working with her that they said to themselves, 'I don't think she is able to do it at all.' I was hanging around and not knowing how much of my voice was going to be used except for a few high notes that she knew she couldn't sustain. In the end, Natalie recorded everything to her own takes and sometimes was even out of synch. My main job was to fix up all the inconsistencies of her original recordings. I had to loop all the vocals after the film was finished.