Six years after David Cassidy broke through came Cassidy 2.0: his half-brother Shaun Cassidy. This one was even cuddlier than the original, and somehow he came off as even less threatening. The late 1970s was a time of intense 1950s nostalgia (Grease, American Graffiti, Happy Days…) and Shaun cashed in on the craze by releasing a cover of "Da Doo Ron Ron" that went to number one. He also stared on the Hardy Boys/Nancy Drew Mysteries on television. It all ended after about three years, but Shaun continued to act on Broadway and on television, occasionally even working with David.