The first scientific investigations of the güevedoces occurred in the 1970s, when Dr. Julianne Imperato-McGinley, an endocrinologist from Cornell University traveled to the village of Salinas (population 4300) in the Dominican Republic to investigate reports of apparently female children becoming male children at the onset of puberty. The cause was determined to be 5α-reductase deficiency, and the results were published in the journal Science in 1974. The frequency of the deficiency was found to be unusually high in Salinas, with occurrence ratio of 1 guevedoce to every 90 normal males.
^Imperato-McGinley, Julianne; Guerrero, Luis; Gautier, Teofilo; Peterson, Ralph Edward (December 1974). "Steroid 5alpha-reductase deficiency in man: an inherited form of male pseudohermaphroditism". Science. 186 (4170): 1213–1215. doi:10.1126/science.186.4170.1213. PMID4432067.