J.K Rowling's comments about transgender people on Twitter have caused widespread controversy, with Stephen King going as far as to shut down the author over trans rights.

Now, Cynthia Nixon has opened up about the effects the Harry Potter author's comments had on her transgender son.

Cynthia Nixon. [[imagecaption|| Credit: PA Images]]

In an interview with The Independent, the 54-year-old said that her 23-year-old transgender son found the author's comments to be "very painful".

"It was really painful for him because so much of his childhood was tied up with Harry Potter. We're a Harry Potter family," explained the former Sex and the City star. "The books seem to be about championing people who are different, so for her to select this one group of people who are obviously different and sort of deny their existence, it's just… it's really baffling."

Nixon added: "I know she feels like she's standing up for feminism, but I don't get it."

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Following the author's controversial comments, the stars of the Harry Potter film series spoke out in defense of transgender rights, beginning with Daniel Radcliffe.

"Transgender women are women. Any statement to the contrary erases the identity and dignity of transgender people and goes against all advice given by professional health care associations who have far more expertise on this subject matter than either Jo or I," he said.

Emma Watson echoed this statement by saying "trans people are who they say they are," and so too did Ruper Grint who said that "trans women are women. Trans men are men."

Nixon's comments come after it was revealed that a number of other authors at J.K Rowling's literary agency quit because of her comments about transgender people, Fox News reports, and Rowling herself decided to return the Ripple of Hope Award to the Robert F. Kennedy Human Rights organization because of the backlash.

Cynthia Nixon admits J.K. Rowling's comments on gender were 'really painful' for trans son