Warren Beatty and Annette Bening's 18-year-old child is reportedly living as a man and planning to transition.
The student is said to be known as Stephen Ira and wears men's clothing to college.
The National Enquirer reports that acting pair Beatty, 73, and Bening, 52, are "devastated" by the news.
A source told the publication: "Warren Beatty is beside himself over the situation with his daughter Kathlyn.
"He and Annette have tried to deal with this over the years when their daughter was younger, but she's determined to go ahead with the transgender operation, just like [Chaz Bono].
"She repeatedly told her parents that once she turns 18 she would take matters into her own hands."
Beatty and Bening have been married for 18 years and have three other children. They have not commented on the reports.
Last year, Chaz Bono, the son of singer Cher, announced he was becoming a man after living as a lesbian for 20 years.
The 40-year-old recently legally changed his name and is thought to be nearing the end of his transition.
Warren Beatty's legendary gold crown for womanizing is about to get some added polish, with this week's publication of his authorized biography, Star: How Warren Beatty Seduced America.
"Using simple arithmetic," author Peter Biskind calculates, according to New York Post, Betty bedded "12,775 women, give or take, a figure that does not include daytime quickies, drive-bys, casual gropings, stolen kisses and so on."
Among Beatty's conquests, Biskind writes, the Bonnie and Clyde, Heaven Can Wait and Reds star-producer can claim Jane Fonda (who at first thought her costar was gay), Joan Collins (whom he exhausted), Leslie Caron, Isabelle Adjani, Julie Christie, Diane Keaton, Madonna and, of course, the woman the now-72-year-old Beatty married in 1992, Annette Bening.
For a time, it appeared Beatty might even have done an on-camera love scene with his older sister, Shirley MacLaine, who was up for the lead opposite her brother in 1967's breakthrough Bonnie and Clyde.
Only that was not to be. Bonnie Parker was played by Faye Dunaway, whose career was then launched. But as MacLaine said in an oft-quoted line, "I'd love to do a kissing scene with him, to see what all the fuss is about."
She also said, "I keep my daughter as far away from Warren as possible!"
Warren Beatty and Annette Bening's 18-year-old child is reportedly living as a man and planning to transition.
"She repeatedly told her parents that once she turns 18 she would take matters into her own hands."
