Tall men in the Netherlands have more children than their short buddies, so they tend to produce more tall men, who go on to have generally tall babies. Dutch women of medium height are more likely to have a partner than their long-legged counterparts, and so (on average) have the most children. Being a lady of middling height means that plenty of men are taller than you, which Dutch women find desirable in a partner (again, on average—no offense to the women of the Netherlands who've got a thing for short men, or tall women, or, you know, whoever). If you're a tall woman, it's harder to find a man who can tower over you. But those tall women who do partner up actually end up having the most children of all, so the country's reproductive habits are basically geared to produce increasingly giant babies.