“Prodigy” derives from the Latin “prodigium,” a monster that violates the natural order. These children have differences so evident as to resemble a birth defect, and it was in that context that I came to investigate them. Having spent 10 years researching a book about children whose experiences differ radically from those of their parents and the world around them, I found that stigmatized differences — having Down syndrome, autism or deafness; being a dwarf or being transgender — are often clouds with silver linings. Families grappling with these apparent problems may find profound meaning, even beauty, in them. Prodigiousness, conversely, looks from a distance like silver, but it comes with banks of clouds; genius can be as bewildering and hazardous as a disability. Despite the past century’s breakthroughs in psychology and neuroscience, prodigiousness and genius are as little understood as autism