The Cowsills - The rain, the park and other things The band was formed in the spring of 1965 by brothers Bill, Bob, and Barry Cowsill; with their brother John joining shortly thereafter. Originally Bill and Bob played guitar and Barry played the drums. When John learned to play drums and joined the band, Barry began playing bass. After their initial success, the brothers were joined by their siblings Susan and Paul along with their mother, Barbara. A seventh sibling, Bob's twin brother Richard,