Paediatric genetics involves multiple visually based diagnostic processes. While examining the external features of a child plays an important role, of increasing importance are biochemical analyses of blood, which produce digital diagrams that display variations in the shape and composition of chromosomes. The level of magnification and detail that can now be captured is allowing new patterns of variation to be ‘seen’ and possible diagnosis to be made, which were not possible before. However, this generates questions about whether these forms of genetic diagnosis and digital visualisation are increasing the scope of medicine to define the body as ill – regardless of whether symptoms are present. This article, drawing from research in a paediatric genetic service, cautions against giving too much power to digital imagery. It does so by arguing that the imagery is only one source of visualisation relevant to how the child’s body is read and understood.