M.F.S.B. -- or Mother Father Sister Brother -- were a Philadelphia-based collective drawn together through their studio work for the legendary songwriting team Gamble and Huff. Having backed the best of the Philly soul crop (including the Spinners and the O'Jays), M.F.S.B. began playing and recording on their own, releasing their eponymous debut in 1973. The album showcased the collective's fondness for deep soul grooves and extended jazz-influenced jams, and sold respectably. Later that year, Don Cornelius approached Kenny Gamble about writing a theme song for his newly syndicated television show, Soul Train. Gamble gathered the members of M.F.S.B. into the studio with vocal group the Three Degrees, and recorded what would later be called "T.S.O.P.," which stands for "The Sounds of Philadelphia." The song proved immensely popular, topping pop and R&B charts. M.F.S.B. would go on to record more albums (flirting with disco in a couple of them), but waning interest led the group to disband after 1980's Mysteries of World.