We keep sequencing genomes as though the answers to human suffering are written in base pairs. They are not. The stubborn fascination with genetic explanations for health outcomes is not merely insufficient—it is a distraction from the forces that actually shape who gets sick and who stays well. Social determinants of health—those structural, economic, and environmental conditions that dictate the contours of daily life—account for far more variation in health outcomes than any polygenic risk score ever will. And the evidence for this is not subtle. It is overwhelming, repetitive, and consistently ignored by people who would rather believe that disease is written into our DNA than confront the political and economic realities that make people ill.
The Genetic Explanation Is Seductive—And Incomplete
Let us be clear about what genetics actually explains. Genome-wide association studies have identified thousands of variants associated with various diseases. For most common conditions—heart disease, type 2 diabetes, depression—each individual variant explains a fraction of a percent of the variance in outcomes. Even combined into polygenic risk scores, the predictive power remains modest. A 2020 study in Nature Genetics found that polygenic scores for coronary artery disease explained roughly 4-5% of variance in disease risk. By contrast, traditional risk factors like smoking, diet, and socioeconomic status explained substantially more.
This is not an argument that genetics does not matter. Of course it does. Monogenic disorders like cystic fibrosis or Huntington’s disease demonstrate that single genes can produce devastating illness. But these conditions are rare. The vast majority of disease burden in any population comes from conditions where environment, behavior, and structural factors dominate. When we focus on genetics, we are explaining the margins, not the main event.
What Social Determinants Actually Encompass
The term “social determinants of health” gets thrown around so casually in medical education that it has nearly lost its meaning. So let us be specific. Social determinants include:
- Income and economic stability—not just whether you can afford medication, but whether you can afford to live in a neighborhood with clean air, safe housing, and grocery stores that sell fresh food.
- Education—not merely years of schooling, but the quality of that education and the economic opportunities it unlocks.
- Neighborhood and built environment—the physical conditions that determine whether walking is safe, whether parks exist, whether pollutants concentrate in your zip code.
- Healthcare access and quality—whether you have insurance, whether providers listen to you, whether your nearest hospital is thirty minutes or thirty seconds away.
- Social and community context—discrimination, social support, incarceration history, civic participation.
Each of these categories contains dozens of specific, measurable factors that independently predict health outcomes. They do not merely “contribute” to disease. They generate it. They produce the gradient we see across every health metric: the steep, consistent correlation between social position and mortality that has been documented in every industrialized nation studied.
The Evidence Is Not Close
Consider the following. In the United Kingdom, the Marmot Review demonstrated that people in the poorest neighborhoods die, on average, seven years earlier than those in the wealthiest—and spend more of their shorter lives in poor health. That gap is not driven by genetic differences between postcodes. It is driven by the material conditions of life: work, housing, stress, food, pollution, and the cumulative biological toll those conditions exact.
A World Health Organization synthesis of global data estimates that social determinants account for 30-55% of health outcomes overall. Genetic factors, even broadly construed, do not come close. And within populations of shared genetic ancestry—comparing, say, second-generation immigrants from the same region living in different socioeconomic conditions in the same country—the health differences remain enormous. Same genes, different environments, radically different outcomes.
The Case of Migration Studies
Migration studies make this point with brutal clarity. When populations move from low-income to high-income countries, their disease profiles shift to match the host nation within a generation. Japanese immigrants to the United States develop coronary heart disease rates far exceeding those of their relatives who remained in Japan, approaching the rates of white Americans. Their genes did not change. Their food, their activity patterns, their stress levels, and their social environments did.
Why This Makes People Uncomfortable
There are several reasons the genetic explanation retains such cultural force despite its limited explanatory power. First, it is individual. Genetic narratives align with a worldview that locates cause—and therefore responsibility—inside the body. If your disease is in your DNA, then it is yours alone. If your disease is a product of economic inequality, residential segregation, and food deserts, then it is a collective failure. And collective failures demand collective solutions, which require political will and resource redistribution.
Second, genetic explanations are comforting to those in power. If health disparities reflect genetic differences rather than social ones, then no policy intervention is needed—or even warranted. The status quo is naturalized. This is not a new phenomenon. The history of using genetics to justify inequality is long and ugly, from eugenics to The Bell Curve to contemporary fetishization of personalized medicine.
Third, genetic research is fundable. Pharma and biotech see profit in genetic data. There is no comparable financial incentive for demonstrating that housing policy is medicine, that minimum wage laws are public health interventions, that desegregating schools reduces disease burden downstream.
The Biological Embedding of Social Conditions
One objection persists: if social conditions matter so much, then what is the mechanism? How does a zip code get under the skin? This is a reasonable question, and we now have answers. Chronic stress from economic insecurity, racial discrimination, and social isolation activates the hypothalamic-pituitary-adrenal axis repeatedly and persistently. Cortisol dysregulation, inflammatory marker elevation, accelerated telomere shortening, and epigenetic modifications—all of these have been documented in populations experiencing social disadvantage.
Notice what this means. The biological mechanisms exist. We can measure them. They are real physiological processes. But they are responsive to social conditions, not to genetic inheritance. Epigenetic modifications triggered by childhood poverty are not “genetic” in any meaningful sense—they are environmentally induced changes in gene expression that can, in some cases, be reversed if the social conditions change.
Conflating these mechanisms with “genetics” is not just a category error. It is a strategic one. It directs resources and attention toward mapping the genome when we should be mapping the food desert. It funds another SNP chip when we should be funding affordable housing.
What a Serious Response Would Look Like
If social determinants explain more than genetics, then our public health infrastructure should reflect that reality. It currently does not. The National Institutes of Health devote approximately 4-5% of their budget to social determinants research. Private investment in social interventions is dwarfed by biotech spending on genomics. Medical education still treats social determinants as a curricular afterthought—a two-hour lecture sandwiched between pharmacology blocks—rather than the central organizing framework for understanding disease.
A serious response would treat housing policy as health policy. It would treat education funding as health spending. It would recognize that the most effective cardiovascular intervention available is not a statin—it is a living wage. These are not radical claims. They are empirically supported. What is radical is the continued refusal to act on them.
Frequently Asked Questions
Does this mean genetics is irrelevant to health?
No. Genetics explains rare monogenic disorders, contributes to susceptibility for common diseases, and has important clinical applications in pharmacogenomics and cancer treatment. The argument is about proportion—about where the majority of population-level health variation comes from, and therefore where the majority of our attention and resources should go. For most common diseases affecting most people, social conditions swamp genetic effects. That is simply what the data show.
Can’t we address both genetics and social determinants simultaneously?
In principle, yes. In practice, resource allocation is zero-sum. Every dollar spent on another genome-wide association study is a dollar not spent on evaluating housing interventions, nutrition programs, or income support policies. More importantly, the framing matters. When we present genetics as the primary explanation for health disparities, we do not merely understate social determinants—we actively undermine the political will to address them. The public and policymakers absorb the message that disease is individual, biological, and largely fixed. That message is wrong, and its consequences are measurable in preventable deaths.
How can social determinants be more important than biology? Disease is biological.
Disease manifests biologically. That is not in dispute. But the question is not whether disease is biological—it obviously is. The question is what produces the biological dysfunction. When a child develops asthma because she lives in substandard housing with mold and cockroach allergens, the asthma is biological. The cause is not genetic. It is a landlord who will not remediate, a housing market that concentrates poverty, and a regulatory system that tolerates it. Calling something “biological” describes where it appears. It does not explain why it appears. For that, you have to look at the conditions that generated the biology—and those conditions are, overwhelmingly, social.