So one question is, if you normalize nutrition, what's the intrinsic height difference between populations? You are correct that the speed at which the Dutch have overtaken other nearby populations is kind of surprising. A nutrition differential could make that much difference, but it seems like general nutrition shouldn't differ much at all between the Dutch, the Belgians, the French, etc. Another possibility is just the the Dutch are genetically a little bit taller on average if you normalize nutrition. But it doesn't seem like Dutch genetics should differ that much from the surrounding populations either. Could natural selection have made that much difference in Dutch genetics in just a few generations, and recent (post Industrial Revolution) generations at that?
