Other people have already mentioned nutrition, which is very important. But scientists have also theorized that part of the reason for the Netherlands having the highest average height is that women in that country have preferred men who are taller, more than in other countries.

In response to your question, I don’t think so, that would be very strange. The only way I could think of that the size of a country and the height of its people would correlate is if bigger countries tend to have higher GDPs per capita, allowing people more money so they can get proper nutrition from food. However, I don’t think size of country and GDP per capita correlate much, but I could be wrong.