When he was thirteen, his mother Judith died from a malignant brain tumor, an event which he has said haunted him and has strongly affected his writing.
His parents divorced when Lethem was young. Lethem later said Dick's work was "as formative an influence as marijuana or punk rock-as equally responsible for beautifully fucking up my life, for bending it irreversibly along a course I still travel." He gained an encyclopedic knowledge of the music of Bob Dylan, saw Star Wars twenty-one times during its original theatrical release, and read the complete works of the science fiction writer Philip K. Despite the racial tensions and conflicts, he later described his bohemian childhood as "thrilling" and culturally wide-reaching. 29 in nearby Cobble Hill was future New York City Schools Chancellor Carmen FariƱa, whom he called the "perfect" teacher and to whom he dedicated his first novel, Gun, with Occasional Music.
The family lived in a commune in the pre- gentrified Brooklyn in the northern section of the neighborhood of Gowanus (now called Boerum Hill). His brother Blake became an artist involved in the early New York hip hop scene, and his sister Mara became a photographer, writer, and translator. His father was Protestant (with Scottish and English ancestry) and his mother was Jewish, from a family with roots in Germany, Poland, and Russia. Lethem was born in Brooklyn, New York, to Judith Frank Lethem, a political activist, and Richard Brown Lethem, an avant-garde painter.