"My mother was -- is very old-school regarding money and tough love," she said.
Unable to afford college, Parker worked as a maid, waitress and stewardess.
"I would look up, and the in-flight movie would be 'The Turning Point' or another [MacLaine] movie. And it would be a moment that I would find that I could be with her. She was right there. And I would just yearn for her," Parker said.
Parker really wanted to be an actress, but she says her mother did little to help. She landed bit parts in "Peggy Sue Got Married" and "Back to the Future," but her career never took off. In 1986, she and her mother made a Diet Pepsi commercial.
"Oh honey, you learn more from failure than success," MacLaine said in the ad.
"That's kind of her," Parker said with a laugh. "Perhaps she wrote the script. I don't know."
MacLaine became a bestselling author of New Age books, in which she wrote about her belief in reincarnation and UFOs. During this period, Parker said, MacLaine told her that the man Parker was living with was not her father, but rather his clone. Her real father was "Paul," who was orbiting in space at a cost of $60,000 per month that MacLaine had to pay.
At the time, Parker kept her disbelief to herself to protect MacLaine's feelings, she said. Now, she said, she does not believe MacLaine had "a screw loose"
"I choose to believe that ... she was wide-eyed and so full of wonder."
Today Parker is a single mother with two children: a 16-year-old son and a 14-year-old daughter. She said her relationship with her daughter is healing, but she is still looking for a Hollywood ending with her mother. They last spoke over the summer.
"I try to understand her," she said. "I find myself wanting to protect her so badly, because I so love her. ... And yet the pain is very deep. I would hope that she would own it and apologize. That would really, really be wonderful."
Parker said she hoped MacLaine would "see the positive" in her book. She sent her a copy with a note saying, "I love you."
Watch the Full story on "20/20: Stars, Scars and Showbiz Kids" TONIGHT at 10 p.m. ET