[yterdy]

Taking this tangent and riding it: it's well-known that undiagnosed celiac disease in children stunts growth. After diagnosis and transition to a gluten-free diet, there is usually a period of catch-up growth (which unfortunately does not close the gap fully, usually). If there are a bunch of these silent sources of malnutrition, it could - alongside things like poor perinatal care for mothers and children, as well as the various sequelae of America's high level of economic inequality among developed nations - be one piece of the puzzle for why the adult height of Americans has stalled when compared to Europe (which would be an empirical finding and not just gussied-up scientific racism).