She was born in New York City, to her parents Judith and Gérard Louis-Dreyfus. Julia’s American-born mother was a writer and special needs tutor, and her French-born father chaired the Louis Dreyfus Company. In 1962, one year after her birth, her parents divorced.
After moving to Washington, D.C., when Julia was four, her mother married L. Thompson Bowles, dean of the George Washington University Medical School. Julia gained a half-sister Lauren Bowles, also an actress. Due to her stepfather’s work with Project HOPE, she spent her childhood in several states and countries, including Colombia, Sri Lanka, and Tunisia.