Stewart was born Jonathan Stuart Leibowitz in New York City, to Marian (nÃ©e Laskin), a teacher and later educational consultant, and Donald Leibowitz (died June 8, 2013), a professor of physics at The College of New Jersey and Thomas Edison State College. Stewart's family emigrated to the U. S. from Poland, Ukraine and Belarus (thus also making him a Litvak); one of his grandfathers was born in Manzhouli (now part of Inner Mongolia). Stewart is the second of four sons, with older brother Lawrence and younger brothers Dan and Matthew. Stewart's parents divorced when Stewart was eleven years old, and Stewart was apparently largely estranged from his father. Because of his strained relationship with his father, which he described as "still 'complicated'" in 2015, he dropped his surname and began using his middle name, Stuart. Stewart stated, "There was a thought of using my mother's maiden name, but I thought that would be just too big a fuck you to my dad. . . Did I have some problems with my father? Yes. Yet people always view [changing my surname] through the prism of ethnic identity. " He would have his surname legally changed to Stewart in 2001. Stewart and his brother Lawrence, who was previously the Chief Operating Officer of NYSE Euronext (parent company of the New York Stock Exchange), grew up in Lawrenceville, New Jersey, where they attended Lawrence High School. According to Stewart, he was subjected to anti-Semitic bullying as a child. He describes himself in high school as "very into Eugene Debs and a bit of a leftist. "