The Winklevoss twins - Cameron and Tyler - became famous for suing Mark Zuckerberg, claiming he stole their idea for Facebook. This week it was announced they'd made a fortune from Bitcoin. They're former Olympic rowers, and also rowed for Oxford in the 2010 Boat Race. Becky Milligan explores their early life, including talking to their Dad, to discover what drives their ambition. Producers: Smita Patel and Beth Sagar-Fenton.