Greg Marshall grew up with parents battling health issues: cancer and ALS. Marshall had his own health scares – he struggled with his leg and mobility his whole life, which his mom and dad said was a result of tight tendons. As an adult, he found out he'd actually been diagnosed with cerebral palsy at birth. His memoir, Leg:The Story of a Limb and the Boy Who Grew from It, is an intimate, funny and honest look at Marshall's journey with his body and sexuality. He tells NPR's Scott Simon why he wanted to open up about living with a disability and why he wanted his leg to be the star of the show.