Remembering an unhappy childhood, with a cold, distant mother who was "always away," Sontag lived in Long Island, New York, then in Tucson, Arizona, and later in the San Fernando Valley in Southern California, where she took refuge in books and graduated from North Hollywood High School at the age of 15.
Sedem let kasneje se je njena mati poročila s kapetanom Ameriške vojske Nathanom Sontagom.