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← All research storiesMigration evidence

Same Genes, Different Dinner Table

When people of Japanese ancestry moved from Japan to Hawaii to California, their genes traveled — but their environment changed. So did their disease patterns.

Migration StudyObservational
California. Most Westernized diet and lifestyle; coronary heart disease generally highest. The most acculturated group showed several-fold higher CHD than the most traditional.

Illustrative direction only — not exact values, and not a reproduction of any published figure.

What changed

As men of Japanese ancestry moved from Japan to Hawaii to the U.S. mainland — and across later generations of Japanese Americans — their surroundings became more Westernized. Habitual diet, physical activity, body-fat patterns, and the broader social setting all shifted. Researchers measured this as a gradient of acculturation, not a single, tidy diet swap.

What showed up

Coronary heart disease was generally lowest among men in Japan, higher in Hawaii, and highest in California, while stroke tended to run the other way (higher in Japan). Decades later, Japanese Americans studied in Seattle showed type 2 diabetes prevalence far above figures reported for residents of Japan, with visceral (abdominal) fat highlighted as a key correlate. The disease patterns drifted toward those of the host environment as acculturation increased.

Held constant

Same genes

The people in these studies share Japanese ancestry. Genetics travels with them from Japan to Hawaii to California.

What changed

Different environment

Diet, activity, body-fat patterns, and daily life Westernized along the way — and the disease patterns moved with the environment.

What it suggests

  • Moving into a Western environment tracked with a shift toward Western disease patterns in genetically similar people.
  • In the acculturation analysis, the most Westernized group had several-fold higher coronary heart disease than the most traditional group — a gap that standard risk factors did not fully explain.

What it does not prove

  • It cannot show that diet alone caused the changes. Smoking, physical activity, body-fat distribution, stress, and healthcare or screening differences all varied too.
  • Comparisons across populations and eras (for example, Seattle today vs. Tokyo) are not controlled experiments, and who migrates or keeps traditional habits is not random.
The takeaway

Migration studies are compelling precisely because the genes travel while the dinner table changes — but a strong clue is still a clue, not proof.

Sources & citations (4)Tap to open
  1. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: prevalence of coronary and hypertensive heart disease
    Marmot MG, Syme SL, Kagan A, Kato H, Cohen JB, Belsky J · American Journal of Epidemiology 102(6):514–525 · 1975
  2. Acculturation and coronary heart disease in Japanese-Americans
    Marmot MG, Syme SL · American Journal of Epidemiology 104(3):225–247 · 1976
  3. Honolulu Heart Program (HHP)
    National Heart, Lung, and Blood Institute (NHLBI) · NHLBI BioLINCC, National Institutes of Health · cohort begun 1965
  4. The Japanese American Community Diabetes Study and the 'canary in the coal mine' (Yutaka Seino Award Lecture)
    Fujimoto WY · Journal of Diabetes Investigation 7(5):664–673 · 2016

We summarize these sources in our own words and link to the originals. Summaries can simplify nuanced findings — follow the links for the full picture.