90% of Diseases Depend on "Environment"? Air, Work, and Wallet Are More Important Than DNA: Environmental Factors Take Center Stage in Disease Risk

Genetics or Environment? The Long-Standing Debate is Shifting to "Both are Correct"

"This illness is just my constitution, so there's nothing I can do," "It's hereditary, so I've given up."
Such phrases have existed as a matter of course in our daily lives.

However, in recent years, research results suggesting that "environmental factors are more significant than genetics" have been emerging one after another. An article distributed by UPI/HealthDay at the end of November 2025 is one such example. The title is "Environmental Triggers Rival Genetic Factors in Disease Onset."Upi

The straightforward narrative that a single gene determines a disease does not seem to sufficiently explain reality. The air we breathe every day, the water we drink, the food we eat, our work environment, stress, income, and the area we live in—these accumulations of various "environmental exposures" are now seen as significantly influencing disease risk.ERS Publications

"90% Environmental Factors?" The Impact Shown by Exposome Research

There is a number that symbolizes the importance of environmental factors.
According to reports from the European Parliament and international reviews, up to 90% of disease risk may be related to environmental factors.European Parliament

Furthermore, studies using the concept known as the exposome suggest that for some chronic diseases, 70-90% of the risk can be explained by environmental exposure.ABC

The exposome refers to

"the totality of environmental exposures from conception to death"ERS Publications

. It includes both visible and invisible factors such as air pollution, noise, workplace stress, night shifts, diet, chemicals, and heatwaves from climate change.

On the other hand, a study using data from the UK Biobank involving 500,000 people reported that environmental and lifestyle factors account for about 17% of the risk of early death, while genetics account for about 2%.University of Oxford

Of course, the proportions vary by disease, but at the very least, the image that "everything is determined by DNA" seems to be quite disconnected from reality.

What "Environmental Triggers" Cause Diseases?

When hearing about environmental factors, air pollution might be the first thing that comes to mind. In fact, it has been shown that in areas with high concentrations of fine particulate matter (PM2.5) and nitrogen oxides, the risk of cardiovascular and respiratory diseases increases, and in some cases, it can also affect cognitive function and bone health.German Center for Cardiovascular Research

However, "environmental triggers" are not limited to just that.

• Chemicals: Endocrine disruptors from pesticides and plastics are linked to hormonal imbalances, obesity, infertility, and developmental disorders.Wikipedia

• Work and Income: Unemployment, long working hours, and low income increase the risk of many diseases, including depression, heart disease, and diabetes.University of Oxford

• Lifestyle: Smoking, lack of exercise, excessive drinking, and a diet centered on processed foods are almost universally linked to major chronic diseases.University of Oxford

• Living Environment: People living near busy highways, in areas with little greenery, or in noisy regions have higher risks of chronic diseases compared to those who do not.University of Oxford

These factors not only act individually but also attack simultaneously as a "mix", further complicating the problem.

Genes and Environment are Not "Addition" but "Multiplication"

As the UPI/HealthDay article title suggests, researchers are not interested in competing over "which is more dominant, genetics or environment." What is more important is the interaction between the two.

In a study on an autoimmune disease, it was shown that people exposed to "high genetic risk + high air pollution" had a much higher risk of developing the disease than those exposed to only one of these factors.Health

Such "multiplicative effects" are thought to trigger disease when combined with

• a genotype that is sensitive to certain chemicals

• a constitution that easily releases stress hormones
  .

On the other hand, cases are emerging where "improving the environment can negate the effects even if the genetic risk is high." This might be the greatest hope that exposome research brings.

What Reactions Can Be Imagined on Social Media?

When this article's theme flows into social media, the timeline will likely be filled with posts like these (not actual posts, but typical reaction images):

• "I was resigned to diabetes because my parents and grandparents had it, but maybe it's not too late if I change my environment... I feel a bit hopeful."

• "If disease risk is determined by 'where you live and your income' rather than genetics, isn't it a problem beyond individual effort?"

• "If the environment is so important, companies and governments have an obligation to clean the air and water more. It's not fair to just impose 'personal responsibility' on individuals."

• "Exposome research is amazing. There might be services that predict future risks by combining with my daily activity logs."

On X (formerly Twitter) and Threads,

• "Fear" (many factors are beyond personal control)

• "Anger" (frustration with inadequate environmental policies)

• "Expectation" (new possibilities for prevention and healthcare)

are likely to become a complexly intertwined discussion.

Health Disparities That Cannot Be Explained by "Personal Responsibility"

The tricky part about environmental triggers is that they are strongly linked to social inequality.

People who have no choice but to live near heavily polluted industrial areas, those who lose sleep due to night shifts and long working hours, and those who have to rely on cheap but low-nutrient processed foods—research shows that these individuals tend to be exposed to multiple environmental risks simultaneously compared to those living in affluent areas, resulting in a disproportionate burden of chronic diseases.University of Oxford

Viewing disease as a "problem of individuals who cannot manage themselves" obscures these structural factors. Data suggesting that environmental impacts are greater than genetic ones can exert pressure not only on "individual efforts" but also on macro policies such as urban planning, labor policies, and climate change measures.

What We Can Do Starting Today

That said, while it may be difficult to change national-level policies immediately, there are indeed environmental factors that individuals can control. Based on research and recommendations from expert organizations, the following points can be realistic starting lines.University of Oxford

1. Be Conscious of Air Quality

   • Change your commuting route to avoid roads with heavy traffic

   • Avoid intense outdoor exercise on days with severe air pollution and switch to indoor exercise

2. Build "Small Habits"

   • Walk one station, use stairs instead of elevators

   • Reduce smoking (complete cessation is ideal, but even reducing helps lower risk)

3. Update Your Food Environment

   • Change from eating processed foods and fried foods daily to "several times a week"

   • Increase the number of times you cook at home (improving the environment by choosing your own ingredients)

4. Improve Your Mental Environment

   • Reduce "overexposure" to social media and news, and ensure sleep time

   • Avoid isolation and maintain connections with trusted people

5. The Option of Raising Your Voice

   • Participate in petitions and civic movements demanding measures against local air pollution, noise, and heat islands

   • Engage in consumer behavior that emphasizes environmental considerations and working conditions of companies

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