I think this point was not well explained, and what she meant was that the doctor was perplexed not by the kid being 1st percentile but at the calm that the par

I think this point was not well explained, and what she meant was that the doctor was perplexed not by the kid being 1st percentile but at the calm that the parents kept, their seeming acceptance of the situation. Which is also what is implied by the rest of the story.