Possibly diet. Obviously it's anecdotal but all of the Dutch people I know consume far more dairy products than those from the UK.
Edit: Turns out the Dutch are the third biggest consumers of milk per capita in the world[0], looking at the list of "tallest" countries on wikipedia[1], there seems to be a great deal of overlap at the top of the two lists. I wonder if a secondary factor could also be related to vitamin D exposure, but I couldn't find a data source for that.
Over 2,000 years ago Julius Caesar described the people that lived where The Netherlands, Belgium, and Germany are today.
> They do not live much on corn, but subsist for the most part on milk and flesh, and are much [engaged] in hunting; which circumstance must, by the nature of their food, and by their daily exercise and the freedom of their life (for having from boyhood been accustomed to no employment, or discipline, they do nothing at all contrary to their inclination), both promote their strength and render them men of vast stature of body.
It was unquestionably propaganda, Caesar paints himself in the best possible light most of the time, but there is no one who questions the overall historical accuracy. Most of Caesar's military and political life is confirmed by many other sources and pieces of evidence.
Perhaps they've always been taller and were suppressed by two world wars and famine etc and have since bounced back. Maybe the starting point of 150 years ago is the issue. (
Edit: Turns out the Dutch are the third biggest consumers of milk per capita in the world[0], looking at the list of "tallest" countries on wikipedia[1], there seems to be a great deal of overlap at the top of the two lists. I wonder if a secondary factor could also be related to vitamin D exposure, but I couldn't find a data source for that.
0. https://en.wikipedia.org/wiki/List_of_countries_by_milk_cons...
1. https://en.wikipedia.org/wiki/Template:Average_height_around...