This week's Father's Day edition of "Sunday Morning," hosted by Lee Cowan, features Tony Dokoupil's cover story about an occupational hazard faced by firefighters: cancer. Plus, Tracy Smith talks with comedian and "Toy Story 4" star Tim Allen; Nikki Batiste explores the origins of Father's Day, and talks with the self-proclaimed "World's Best Father"; John Blackstone looks at the history of the building of the Transcontinental Railroad; Nicholas Thompson interviews bitcoin billionaires Cameron and Tyler Winklevoss; and David Pogue enters the virtual world of the blockbuster video game Minecraft.