Nutrition clearly affects height, but I have long wondered whether there is a psychological or social component. I know of zero scientific evidence for this, but I wonder if it is possible for populations to grow taller because of social/psychological expectations. The rich have always been taller than the poor, but maybe it's not entirely because they eat better but because they feel in some sense entitled to height? Sounds crazy, but many things one wouldn't expect are affected by social status. E.g., people of relatively lower status die younger than people of higher status even when both groups are within the privileged class where access to medical care isn't a factor. I.e., the bosses statistically outlive the underlings even when everyone is upper middle class. The phenomenon is well known, but the causes are not understood. Many animals undergo profound physical changes in response to the animals around them, such as protogny and protandry, for example, males of some species of some fish with change sex if the dominant female dies. The opposite also occurs. I wonder if people worldwide might be getting taller in part because expectations are changing due to electronic media? It's hard to believe that the Dutch keep getting taller because of better nutrition alone.