"Onze voorouders waren minder lang dan wij."
Translation:Our ancestors were less tall than us.
I actually heard that the Netherlands went from being one of the shorter countries to the tallest country in a relatively short period of time.
Apparently, there is also a genetic component, shared with people in Motenegro and a few other places in Europe. Some reseachers claim this genetic heritage is palaeolithic (https://geneticliteracyproject.org/2017/04/18/dutch-croatians-populations-tall-men-genetically-linked-prehistoric-mammoth-hunters/).