I am not saying I believe in it, but in the past I heard more than once that Dutch were one of the first nations to add more additives to their food and that's why they are this tall.

Also, Dutch people are not the only ones to get taller and taller: even in southern European countries the young generations are experiencing a huge height boost.

Unlikely. https://en.m.wikipedia.org/wiki/Beef_hormone_controversy:

In the 1990s, in the midst of the mad cow disease crisis, the European Union banned the import of meat that contained artificial beef hormones. […] Until 1980, the use of growth hormones, both endogenous and exogenous, was completely prohibited in (as noted above) Italy, Denmark, the Netherlands, and Greece.

Sounds like a monkey sandwich story to me.

I have never heard of a monkey sandwich story but I would really like to hear one.

https://translate.google.com/translate?hl=&sl=nl&tl=en&u=htt... (Google hasn't figured out yet when to translate an idiomatic term literally yet. That makes for a funny translation. See for example the subscript of the first photo)

Same with S Korea. New generation kids are significantly taller than just 1-2 generations ago.

I suspect that the reason South Korean children are taller than they were two generations ago is that two generations ago not having enough food to eat was a real problem in South Korea.

You'd think but such a big jump in height cannot be explained just because of better diet, according to some people. Some think it is because of additive given to cows etc.