Which countries produce the world's tallest people, and why?

Twin studies estimate that 60-80% of height variation within a given population is attributable to genetic factors. However, this figure applies within populations with similar environmental conditions. Between populations with different nutritional histories, environmental factors account for a much larger share of differences. The secular trend over the 20th century is entirely environmental: genes do not change over three to four generations, but average heights have increased by 8cm globally. This demonstrates that even where genetics sets an upper bound, environment determines how close populations get to reaching it. For most people in high-income countries today, they are likely close to their genetic potential; for populations with poor childhood nutrition, there is substantial unrealised genetic height potential.

The Netherlands was not always the world leader in average height. In the mid-19th century, Dutch conscripts averaged 165cm, below many European peers. The dramatic increase over the following 150 years is one of the best-documented examples of the environmental contribution to height. Researchers point to the development of the Dutch dairy industry and high per-capita milk consumption, the universal health insurance system introduced in the early 20th century, and relatively equitable distribution of nutrition and healthcare. There may also be a selection effect: taller Dutch men have historically had slightly more children than shorter men, a rare case where natural selection may have contributed to the national average.

Stunting is defined by the WHO as height-for-age more than 2 standard deviations below the WHO Child Growth Standards median. It is caused by chronic malnutrition, particularly protein and micronutrient deficiency, during the first 1,000 days of life (conception to age 2). Stunting permanently reduces adult height: it cannot be reversed by improved nutrition later in childhood. Approximately 149 million children globally were stunted in 2024, concentrated in South Asia, sub-Saharan Africa, and parts of Central America. The countries with the lowest average heights in the NCD-RisC dataset (Guatemala, Timor-Leste, Bangladesh) all have stunting prevalence above 30% in children under 5.

Yes, significantly in many countries. In most high-income countries, people born in the 1980s are on average 2-4cm taller than those born in the 1950s, reflecting the secular trend. In East Asian countries like South Korea, the generational difference is far larger: South Korean men born in the 1980s are approximately 5-6cm taller than those born in the 1940s. In some low-income countries, the secular trend has stalled or reversed during periods of economic contraction. North Korea is a documented case where average height decreased during the famine years of the 1990s, creating a measurable height gap between North and South Koreans of the same age.

UK men average 175.8cm and women 161.9cm according to NCD-RisC data, placing the UK at approximately 35th for men and 38th for women globally. This puts British men roughly 6-7cm below the Balkan and Northern European leaders, and approximately 2-4cm below France, Germany, and Sweden. The UK average is similar to Italy and slightly above Spain. Among English-speaking countries, Australian men (179.2cm) and Canadian men (178.1cm) are notably taller than UK averages, which researchers attribute partly to selective immigration policies that have historically favoured younger, healthier applicants, and partly to dietary differences.