The Gregarious Brain Nicki Hornbaker, born with Williams syndrome, prepares a cartwheel for her mother. By DAVID DOBBS Published: July 8, 2007 If a person suffers the small genetic accident that creates Williams syndrome, he’ll live with not only some fairly conventional cognitive deficits, like trouble with space and numbers, but also a strange set of traits that researchers call the Williams social phenotype or, less formally, the “Williams personality”: a love of company and conversation combined, often awkwardly, with a poor understanding of social dynamics and a lack of social inhibition. The combination creates some memorable encounters. Oliver Sacks,...