The co-creator of 1990s US sitcom Friends has admitted it was "a mistake" not to use the appropriate pronoun for Chandler's transgender parent.
Marta Kauffman said she now regrets the representation of the character, who was played by Kathleen Turner.
"We kept referring to her as Chandler's father, even though Chandler's father was trans," she said.
"Pronouns were not yet something that I understood. So we didn't refer to that character as she. That was a mistake."
Kauffman was speaking to the BBC World Service's The Conversation in an interview to be broadcast on 11 July.
Turner appeared in the hit sitcom in three episodes in season seven, which was first broadcast in 2001.
Her character was the butt of jokes from others, including Matthew Perry's Chandler and his mother, about her gender identity and appearance.
In a 2018 interview, Turner said she would not take on the role if she was offered it again, and would leave it to a trans woman.
She also said elements of Friends had not aged well, noting how there was confusion over whether the character was a drag queen or a trans woman.
"Yeah, people thought Charles was just dressing up," she told the Gay Times.
The character was not explicitly acknowledged as trans in the programme, being referred to as gay and shown working as a drag artist called Helena Handbasket in Las Vegas.
Kauffman, who is also the creator of the Netflix series Grace and Frankie, said she would do things differently if she was working on Friends now.
Talking about a recent incident on the set of a TV show, she told the BBC she "fired a guy on the spot for making a joke about a trans cameraperson", adding: "That just can't happen."
She went on to say Friends also "did not have enough representation of black people" and that she was "clearly part of systemic racism in our business".
"I was unaware of that, which makes me feel stupid," she said, adding: "That was a very valid, extremely difficult criticism which still... I get emotional about.
"If I knew then what I know now, there are certain things I would have changed. But I didn't know them and I have since learned."
The interview came after Kauffman announced she was donating $4m (£3.3m) to her old university, Brandeis in Massachusetts, to establish an endowed professorship in the school's African and African American studies department.
"Admitting and accepting guilt is not easy," she told the Los Angeles Times last week. "It's painful looking at yourself in the mirror. I'm embarrassed that I didn't know better 25 years ago."