Justin Heckert, writing for New York Times Magazine, spent some time with Ashlyn Blocker and her parents, Tara and John. Ashlyn suffers from a rare condition called congenital insensitivity to pain in which she doesn’t feel pain:

Tara and John weren’t completely comfortable leaving Ashlyn alone in the kitchen, but it was something they felt they had to do, a concession to her growing independence. They made a point of telling stories about how responsible she is, but every one came with a companion anecdote that was painful to hear. There was the time she burned the flesh off the palms of her hands when she was 2. John was using a pressure-washer in the driveway and left its motor running; in the moments that they took their eyes off her, Ashlyn walked over and put her hands on the muffler. When she lifted them up the skin was seared away. There was the one about the fire ants that swarmed her in the backyard, biting her over a hundred times while she looked at them and yelled: “Bugs! Bugs!” There was the time she broke her ankle and ran around on it for two days before her parents realized something was wrong…

The article goes a bit into the genetic reason for Ashlyn’s insensitivity to pain, namely a mutated SCN9A gene. Interestingly, SCN9A.com lists an older NYT article about the gene.