Weiner was born in the New York City borough of Brooklyn, the middle son of his Jewish parents, Mort Weiner, a Lawyer, and his wife Frances (née Finkelstein), a public high school math Teacher. The family lived for a time in the Park Slope neighborhood of Brooklyn. His older brother Seth was 39 years old when he was killed by a hit-and-run driver in 2000. His younger brother, Jason, is a chef and co-owner of several New York restaurants.