Until recently, it was thought that very few people suffer from prosopagnosia. The condition has traditionally been studied in individuals who acquire the disorder following neurological damage (typically from stroke or head injury), and a handful of case studies were reported in the literature in the 20th century. However, it has recently become clear that many more people suffer from prosopagnosia without experiencing neurological damage. This form of the disorder is commonly referred to as "developmental" or "congenital" prosopagnosia, and these individuals simply fail to develop normal face processing abilities despite normal intellectual and perceptual functions. Developmental prosopagnosics have suffered from the face recognition impairment for most of their lives, perhaps since birth. Recent evidence suggests there may be a genetic contribution to developmental prosopagnosia, and several case studies report at least one first-degree relative who also suffers from the face recognition impairment.