Efron was born in San Luis Obispo, California, and later moved to Arroyo Grande, California. His father, David Efron, is an electrical engineer at a power station, and his mother, Starla Baskett, is a former secretary who worked at the same power plant. Efron has a younger brother, Dylan, and had, as he has described it, a "normal childhood" in a middle-class family. He is an agnostic, having never been religious. His surname, "Efron" (עפרון), means "lark" in Hebrew (his paternal grandfather was Jewish).