The 52-year-old former Sex and the City star shared a picture of herself at Samuel's graduation from The University of Chicago
She wrote: 'I'm so proud of my son Samuel Joseph Moses (called Seph) who graduated college this month'
Samuel was born Samantha in November 1996 to Cynthia and her then-partner, and college sweetheart, Danny Mozes
Cynthia and Danny had another son, Charles, born in 2002, and Cynthia also has a third son, Max, with her wife, Christine Marinoni, in 2011
The Instagram post marks the first time that Cynthia, who is running for Governor of New York, has publicly shared that Samuel is transgender
Cynthia Nixon saluted her son Samuel today as the pair celebrate the 14th Annual Trans Day of Action.
The proud mom and former Sex and the City star, who is currently running for Governor of New York, took to Instagram to post a picture of the pair and openly share for the first time that 21-year-old Samuel, born Samantha, is transgender.
'I'm so proud of my son Samuel Joseph Moses (called Seph) who graduated college this month,' she wrote. 'I salute him and everyone else marking today’s #TransDayofAction. #TDOA.'
In the image, the two are seen with their arms around one another, smiling at the camera at Seph's graduation from The University of Chicago; Samuel is dressed in a cap and gown.
Seph was born Samantha Mozes in November 1996 to Cynthia and her then-partner and college sweetheart Danny Mozes.
Cynthia and Danny were together from 1988 to 2003, and also had another son, Charles Ezekiel, who was born in December of 2002.
Shortly after their split in 2004, Cynthia began dating Christine Marinoni, an activist who, until recently, worked for New York City's Deputy Mayor Richard Buery. Cynthia and Christine married in May 2012. They have another son together, Max, whom Christine gave birth to.
Seph has been mostly out of the public eye lately. Though he was occasionally spotted by paparazzi while out with his mom as a little kid, he's been keeping a low profile since Cynthia announced her bid for governor against incumbent Andrew Cuomo.
Cynthia's attended several Pride events this month and in years past, but Seph hasn't yet tagged along or appeared at any campaign stops for his mom.
Yet Cynthia has never really spoken much about any of her kids, keeping her personal life mostly private.
Over a decade ago, she told the what she thought it might be like for her kids at school having a famous mother.
'In a school where everyone is famous or rich or whatever, you have a culture. "What does your dad do?" "What does your mom do?" she said. 'Of course, I’m not saying my daughter doesn’t feel a little like a freak because she has a famous mom.
'At school this morning, she was like, "Go, just go, just go." Which is a kid thing anyway, but you know — I attract attention. When you’re 9, you don’t want that.'
It does seem that Seph has been living as trans for several years now, though this is only the first time that that Cynthia has publicly acknowledged it.
Cynthia has, however, gone to bat for Seph and other trans individuals during her campaign and in her role as LGBTQ advocate.