For about a century, one country kept winning a contest nobody officially entered. The Dutch went from one of Europe’s shorter populations in the 19th century to the top of global height rankings.

Then the gains stopped.

According to Statistics Netherlands, men born in 1980 averaged 183.9 centimetres at age 19, the tallest group in its series. Men born in 2001 came in at 182.9 centimetres. A full centimetre shorter, one generation on.

Women slipped further. Dutch women peaked at 170.7 centimetres for the 1980 group and fell to 169.3 centimetres for those born in 2001, a drop of 1.4 centimetres. The figures come from roughly 719,000 self-reported heights collected through national health surveys run by Statistics Netherlands, local health services and the national public health institute. The estimates cover people born and raised in the Netherlands and calculate average height at age 19 for each birth year.

From below average to the top of the world

To feel how strange the reversal is, you have to see how far the climb went. Dutch men born in 1930 averaged 175.6 centimetres. By the 1980 group they had gained 8.3 centimetres in 50 years. That’s a lot of height to add in two generations, and it happened as the Netherlands became richer, healthier and better fed.

The mainstream explanation is mostly about living conditions. Gert Stulp, a University of Groningen researcher who has studied Dutch height extensively, puts it plainly: “We know if a country gets wealthier with better healthcare and better nutrition and fewer diseases, that increases height.” Diet gets a supporting role. Stulp says the Dutch milk-rich diet is believed to be one cause too.

The scale of the gain points the same way. Over roughly 150 to 200 years, Dutch men added about 20 centimetres. That is far too fast to be explained by genes alone. A later modelling study led by Stulp estimated that natural selection contributed only about 0.07 to 0.36 centimetres of the increase between 1850 and 2000.

What changed after 1980

So why did the run end? 

Statistics Netherlands links part of the decline to immigration from shorter population groups and their Dutch-born children, which lowers the national average without individuals shrinking.

But growth also stalled among people whose parents and grandparents were born in the Netherlands. Among women in that group, the trend turned downward.

Frans Frenken, a statistician at the office, framed the peak carefully. “Previous gains are usually attributed to improvements in nutrition and health care,” he noted. His conclusion was conditional: “If they’ve reached their optimum level then there’s not much more you can do.” Stulp is similarly cautious, calling the causes “very difficult to pinpoint.” The responsible reading is that the plateau is real, but its exact cause remains uncertain.

The taller-genes puzzle

Stulp and colleagues also tested whether natural selection had nudged the Dutch upward. Using data on more than 94,500 people from the northern Netherlands, born between 1935 and 1967, they found taller men tended to have more children. For women, those of roughly average height had the most.

The effect was small. Across the examined height range, the modelled gap between the most and least reproductively successful men was about 0.24 surviving children. It also pointed in the opposite direction from similar research in the United States, where average-height men fathered the most children.

Later simulations found that selection could explain only a tiny fraction of the Dutch rise. It may have been a faint tailwind alongside better conditions, but it cannot explain the rapid climb or why it stopped after 1980.

A ceiling, not a decline

The Dutch are not unusual for levelling off; they were late to it. The NCD Risk Factor Collaboration reanalysed 1,472 population studies covering more than 18.6 million people born between 1896 and 1996. It found Dutch men were the tallest in the latest cohorts, while height gains had already plateaued in the United States, the UK, Finland and Japan. 

Height was never really the point, though. Over the past century, young adults worldwide gained around 10 centimetres on average, and that rise reflected improvements in food, health and living conditions. Height was a stand-in for how good childhood conditions had become.

Seen that way, a plateau at the top is not much of a loss. A centimetre off the tallest population is probably what it looks like when the conditions that drove a century of growth have already done most of their work.