The group was formed at Andrew Jackson High School in Cambria Heights, a neighborhood in Queens, New York City, in 1963. It consisted of two sets of sisters: Mary Weiss (lead singer) (born 1948) and Elizabeth "Betty" Weiss (born 1946), and identical twins Marguerite "Marge" (4 February 1948–28 July 1996) and Mary Ann Ganser (4 February 1948–14 March 1970). The girls often appeared as a trio, as Betty Weiss rarely appeared on stage until late 1965, preferring to avoid touring.