In 2004, the American actress ended her 15 year relationship with English professor Danny Mozes and become romantically involved with education activist Christine Marinoni. The women, who are engaged, are raising the two children Nixon had with Mozes and another child that Marinoni gave birth to last year.
The 45-year-old actress, who has been a vocal advocate of LGBT rights, recently spoke out about her sexuality in an interview with The New York Times to promote her new Broadway play Wit.
"I gave a speech recently, an empowerment speech to a gay audience, and it included the line ĎIíve been straight and Iíve been gay, and gay is better'. And they tried to get me to change it, because they said it implies that homosexuality can be a choice. And for me, it is a choice," said Nixon.
"I understand that for many people itís not, but for me itís a choice, and you donít get to define my gayness for me. A certain section of our community is very concerned that it not be seen as a choice, because if itís a choice, then we could opt out," she said.
"I say it doesnít matter if we flew here or we swam here, it matters that we are here and we are one group and let us stop trying to make a litmus test for who is considered gay and who is not.Ē
She went on to say: ďWhy canít it be a choice? Why is that any less legitimate? It seems weíre just ceding this point to bigots who are demanding it, and I donít think that they should define the terms of the debate. I also feel like people think I was walking around in a cloud and didnít realise I was gay, which I find really offensive. I find it offensive to me, but I also find it offensive to all the men Iíve been out with."
LGBT activists have long argued that being gay or lesbian is not a choice and is either genetic or as a result of influences in the womb. This appears to be backed up by a growing body of scientific research."I donít pull out the 'bisexual' word because nobody likes the bisexuals. Everybody likes to dump on the bisexuals..."
Writing on Americablog, LGBT activist John Aravosis slammed Nixon for her comments, suggesting that while she may not have been born lesbian she was probably born bisexual.
"What she means is that she's bisexual, and doesn't quite get that most people aren't able to have sexual romantic relationships with both men and women because they're just not into both genders. She is into both genders," said Aravosis.
"And that's fine. But she needs to learn how to choose her words better, because she just fell into a right-wing trap, willingly. When the religious right says it's a choice, they mean you quite literally choose your sexual orientation, you can change it at will, and that's bull."
Openly lesbian celebrity chef Cat Cora also criticised Nixon's comments. "I'm gay, and I was born this way," she told The Talk's Julie Chen. "So, I really feel like it was dangerous and irresponsible of Cynthia, especially in this environment today when so many young people are taking their lives."
In a later interview with the Daily Beast's Kevin Sessums, Nixon added that she doesn't like the label of "bisexual," although she suggested that she does in fact see herself as such.
"I donít pull out the 'bisexual' word because nobody likes the bisexuals. Everybody likes to dump on the bisexuals," she said.
When it was pointed out by Sessums that "it is the 'B' in LGBT", Nixon replied: "I know. But we get no respect".
Sessums countered: "You just said 'we,' so you must self-identify as one."
"I just donít like to pull out that word," responded Nixon, "But I do completely feel that when I was in relationships with men, I was in love and in lust with those men. And then I met Christine and I fell in love and lust with her. I am completely the same person and I was not walking around in some kind of fog. I just responded to the people in front of me the way I truly felt."
In a Huffington Post piece, In Defense of Cynthia Nixon: Why 'Born This Way' Doesn't Matter, Tracy Baim wrote that "this nature-vs.-nurture argument has been debated in the LGBT movement for decades".
She went on to say: "I don't think Nixon is wrong to 'choose' how she defines her own life. If the right wing does use her words as a way to attack our community, I don't think it will be any more vile than what they already do. They try to 'cure' us and deny our civil rights no matter what the basis of our true selves.
"We have a common enemy here, and it is not Cynthia Nixon, or those like her who come out as proud in their own unique identity," added Baim.
What do you think? Did you choose to be gay or lesbian? Give us your thoughts below.