One theorized reason for the increase in epidemiological estimates is that a substantial minority of individuals with the genetic markers of WS syndrome lack the characteristic facial features or the diminished intelligence  considered to be diagnostic of the syndrome, and often are not immediately recognized as having the syndrome. History
Williams syndrome was first described by J. C. P. Williams and his colleagues, who wrote in 1961 of four patients with supravalvular aortic stenosis, mental disability, and facial features including a broad forehead, large chin, low-set, "drooping" cheeks, widely spaced eyes, and wide-set mouth. A year after this report, German physician A. J. Beuren described three new patients with the same presentation. This led to the syndromes full original name, Williams-Beuren syndrome, which is still used in some medical publications. From 1964 to 1975, small research reports broadened medical knowledge of this syndromes cardiovascular problems. Then in 1975, K. Jones and D. Smith conducted a large-scale report on numerous patients with WS, ranging in age from infancy to adulthood, and described the behavioral and observable physical symptoms in greater detail than previously recorded. Society and culture
The adjective "elfin" may have originated to describe the facial features of people with WS; before its scientific cause was understood, people believed that individuals with the syndrome, who have exceptionally charming and kind personalities, had extraordinary, even magical, powers.
Dykens and Rosner (1999) found that 100% of those with Williams syndrome were kind-spirited, 90% sought the company of others, 87% empathize with others pain, 84% are caring, 83% are unselfish/forgiving, 75% never go unnoticed in a group, and 75% are happy when others do well. Infants with Williams syndrome make normal and frequent eye contact, and young children with Williams will often approach and hug strangers. People affected by Williams syndrome typically have high empathy, showing relative strength in reading peoples eyes to gauge intentions, emotions, and mental states. The level of friendliness observed in people with Williams is often inappropriate for the social setting, however,  and teens and adults with Williams syndrome often experience social isolation, frustration, and loneliness despite their clear desire to connect to other people.While these children often came off as happy due to their sociable nature, often there are internal drawbacks to the way they act. 76–86% of these children were reported as believing that they either had few friends or problems with their friends. This is possibly due to the fact that although they are very friendly to strangers and love meeting new people, they may have trouble interacting on a deeper level. 73–93% were reported as unreserved with strangers, 67% highly sensitive to rejection, 65% susceptible to teasing, and the statistic for exploitation and abuse was unavailable. There are external problems as well.