How Genetics and Environment Shape Your Immune Health

Why this matters

Understanding that immune conditions arise from a combination of factors rather than a single cause removes the search for one explanation and replaces it with a more accurate picture of how these conditions actually develop.

What genetics contributes

Genes influence how the immune system is built and how it behaves. Certain gene variants affect the strength of inflammatory responses, the efficiency of self-tolerance mechanisms, and the likelihood of producing autoantibodies. These variants are relatively common in the population, which is why autoimmune conditions run in families without being inevitable or predictable.

Carrying a genetic risk factor isn’t the same as having a condition. Many people carry relevant gene variants and never develop symptoms. Genetics creates a vulnerability that environmental factors may or may not activate.

What the environment contributes

Environmental factors are what translate genetic susceptibility into active disease. Infections are among the most studied triggers. Certain viral and bacterial infections appear to initiate or accelerate immune dysregulation in genetically susceptible individuals, sometimes through molecular mimicry and sometimes through broader immune activation.

Chronic stress affects immune regulation in measurable ways, raising baseline inflammation and disrupting the hormonal balance that influences immune function. Significant life events, prolonged psychological stress, and physical stress such as surgery or serious illness have all been associated with the onset or worsening of immune conditions.

Exposure to certain toxic chemicals and environmental pollutants has also been linked to immune dysregulation. Prolonged exposure to substances such as heavy metals, pesticides, and industrial chemicals can disrupt immune function and may contribute to the development of autoimmune conditions in susceptible individuals.

Gut health is increasingly understood to play a role. The gut microbiome, the community of bacteria living in the digestive tract, influences immune regulation in ways that are still being mapped. Disruption to the microbiome through antibiotics, diet, or infection appears to affect immune function more broadly but the exact mechanisms are still being studied.

Why both matter together

Neither genetics nor environment alone is typically sufficient to cause an immune condition. It’s the interaction between them over time that creates the conditions in which dysregulation develops. This also explains why conditions can appear to start after a specific event such as an infection or a period of extreme stress, even though the underlying susceptibility was present long before.

What you could do

• Family history of autoimmune conditions is clinically relevant and worth sharing with the clinical team, as it informs screening and monitoring decisions
• Environmental factors such as stress, sleep, and infection aren’t just background noise. They interact with the underlying immune system in ways that affect disease activity over time and are worth tracking alongside symptoms

This article is for general information purposes only and doesn’t constitute legal, financial or benefits advice. For advice specific to your situation, please speak to a qualified professional or contact an organisation such as Citizens Advice, who may be able to assist you further.

References:

‘Heterogeneity of autoimmune diseases: pathophysiologic insights from genetics and implications for new therapies’ (2015) https://doi.org/10.1038/nm.3897

‘Mechanisms of environmental risk factors for autoimmune diseases’ (2026) https://doi.org/10.1016/j.autrev.2026.104012

‘Role of the microbiota in immunity and inflammation’ (2014) https://doi.org/10.1016/j.cell.2014.03.011

‘Stress as a risk factor in the pathogenesis of rheumatoid arthritis’ (2006) https://doi.org/10.1159/000104855