Largest Twin Study Reveals How Genes Influence Environmental Sensitivity

A study led by King's College London researchers has uncovered genetic variations that may explain why some individuals are more or less sensitive to environmental influences. Published in Nature Human Behaviour, the research explored how genetic sensitivity interacts with environmental factors to impact mental health symptoms, including ADHD, autism, anxiety, depression and psychotic experiences.

The research team, which included collaborators from University College London, Queen Mary University of London and 23 other universities worldwide, analyzed data from 21,792 identical twins (10,896 pairs) across 11 studies. This study represents the largest genome-wide association study (GWAS) of identical twins to date.

Identifying genetic markers linked to environmental sensitivity

The study found several genetic markers associated with variations in environmental sensitivity, particularly in how individuals respond to life experiences. These differences in genetic sensitivity could help explain why identical twins, who share the same genetic makeup, exhibit different levels of psychiatric and neurodevelopmental traits when exposed to the same or different environmental factors.

Among the findings, the researchers identified genes involved in neurodevelopment, immune function and stress response. These genetic variants appeared to influence traits like autistic behaviors, anxiety, depression, psychotic-like experiences and neuroticism. For example, genes related to stress reactivity were linked to depressive symptoms, while those involved in neurodevelopment were associated with autistic traits.

Implications for understanding mental health

The findings of this study are important for understanding the gene-environment interactions that shape psychiatric and neurodevelopmental traits. While both genetic makeup and life experiences influence individual characteristics, the complex interaction between the two has proven difficult to decipher, especially in the context of mental health.

Identical twins, who are nearly genetically identical, provide a unique opportunity to examine these interactions. Differences in traits such as depression or anxiety between identical twins can often be attributed to the distinct environments they experience. By analyzing the genetic data of these twins, the research team was able to identify specific genetic factors that contribute to variations in environmental sensitivity.

Insights into gene-environment interactions

The study also emphasized the importance of family-based designs, such as twin studies, in shedding light on how genes and environmental factors interact to shape mental health outcomes. The international collaboration among the 23 universities was highlighted as a key strength of the research.

The researchers hope that their findings will pave the way for more targeted studies on how specific genetic variants influence environmental sensitivity. Understanding these mechanisms could lead to better ways of addressing psychiatric and neurodevelopmental conditions by considering both genetic and environmental factors.

Reference: Assary E, Coleman JRI, Hemani G, et al. Genetics of monozygotic twins reveals the impact of environmental sensitivity on psychiatric and neurodevelopmental phenotypes. Nat Hum Behav. 2025. doi: 10.1038/s41562-025-02193-7

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source. Our press release publishing policy can be accessed here.