Idina Kim Mentzel was born on May 30, 1971, in Manhattan, New York City. She grew up in New Jersey until about age 3, when her family moved to Syosset, New York, on Long Island. Her parents are Helene Goldberg, a therapist, and Stuart Mentzel, a pajama salesman. She has a younger sister named Cara. Menzel is Jewish, and her grandparents emigrated from Russia. Menzel attended J. Irving Baylis Elementary School in Plainview, New York, and then Syosset's H.B. Thompson Middle School and Syosset High School.