Prosopagnosia refers to a selective difficulty in recognising familiar people by their faces. While it has mostly been documented as a consequence of brain damage due to stroke or traumatic brain injury in people who had normal face recognition prior to the occurrence of this damage, it can also be present from birth (i.e. congenital prosopagnosia). Face recognition in a young boy and girl, both presenting with congenital propspagnosia, was studied. The specific reasons for their impaired face recognition were investigated by using assessment tasks designed to target various of the processing steps involved in face perception, such as the detection of first order relations that define faces (i.e. two eyes above a nose and a mouth), holistic processing (i.e. perceiving the face as a gestalt), and the processing of second order relations (i.e. the spacing amongst facial features). The fact that these two children were siblings suggested that their congenital prosopagnosia might be genetic in origin. Hence face recognition ability in 4 generations of this family was assessed. Some of these family members did show clear impairments of face recognition, strongly suggesting that the children's prosopagnosia was genetically-based.