For millions of people who wonder why anxiety seems to run through generations of their family, scientists may now have part of the answer. A major international study involving nearly 700,000 people has found the strongest evidence yet that genetics contributes to anxiety risk, but researchers say DNA is far from destiny.

The study, published in the journal Nature Human Behaviour and led by researchers from King's College London and the QIMR Berghofer Medical Research Institute in Australia, analysed genetic data from 693,869 people of European ancestry. By examining anxiety symptoms across a broad spectrum rather than simply asking whether someone had a clinical diagnosis, the researchers uncovered 74 locations in the human genome linked to anxiety, the largest number identified so far.

The genome is the body's complete set of genetic instructions. A genome-wide association study, or GWAS, scans the DNA of hundreds of thousands of people to identify genetic differences that appear more often in those with particular traits. In this case, scientists searched for variations associated with more severe anxiety symptoms.

The findings arrive as anxiety disorders continue to rise worldwide, particularly among younger adults. Yet the study suggests that genes explain only a small part of the picture. Researchers estimated that common genetic variations account for around 6% of differences in anxiety severity between individuals.

"Despite the public health impact of anxiety, progress in the understanding of its genetics lags behind other major mental health conditions," said Professor Thalia Eley of King's College London's Institute of Psychiatry, Psychology & Neuroscience. "Given the high and rising rates of anxiety, especially in young adults, it is more important than ever to improve our ability to identify and understand sources of risk."

Among the genes highlighted were PCLO and SORCS3, both involved in communication between brain cells. Many of the new genetic signals were found in genes that are very active in brain tissue, providing new insights into the biological processes that might affect fear, worry, and stress responses.

Yet researchers stress that anxiety is not simply inherited. Scientists increasingly recognise the importance of epigenetics—changes in how genes are turned on or off by life experiences without altering DNA itself. Stressful childhood events, financial hardships, social isolation, trauma, chronic illnesses, and even prolonged uncertainty can all shape mental health outcomes.

"It's important to highlight that genetics interplay with life experiences, social contexts, and psychological factors to shape individual risk," said Dr Megan Skelton, first author of the study. "This means that even someone with a high genetic risk might not develop anxiety, while someone with low genetic risk could."

In simple terms, genes may load the gun, but the environment often pulls the trigger.

The researchers also calculated polygenic risk scores, which combine thousands of tiny genetic influences into a single estimate of inherited risk. However, these scores explained only a modest proportion of anxiety differences, reinforcing that biological predisposition is only one part of a much larger puzzle.

A further interesting finding was the overlap of anxiety with physical health conditions. Depression, migraine, irritable bowel syndrome, chronic pain, coronary artery disease and endometriosis were found to share common genetic links, the study found.

"These correlations highlight the interconnection between mental and physical health," said Dr Brittany Mitchell of QIMR Berghofer. She cautioned that the findings do not prove cause and effect. Living with chronic illness may contribute to anxiety, while some genetic factors could increase vulnerability to both conditions.

The sudy also identified a substantial research gap. Much of the available genetic data is from people of European descent, making it difficult for scientists to understand the risk of anxiety in African and South Asian groups. Researchers say that bigger and more diverse datasets will be key to future breakthroughs.

For now, the message emerging from one of the largest anxiety genetics investigations ever conducted is both reassuring and challenging. While biology matters, it does not seal a person's fate. Understanding who may be more vulnerable could eventually help doctors offer earlier support and more personalised care. However, for reducing anxiety across society will still require tackling the environmental pressures that shape mental health every day.