Family histories of disease not only influenced by genes

Shared eating habits and living spaces could be missing link, researchers say. Picture: David Moir

Family history of diseases such as cancer and Alzheimer's may be caused by shared living habits and surroundings rather than genetics, new research suggests.

Edinburgh University researchers found that scientists could overestimate the importance of genetic variation of disease by up to 47 per cent by failing to consider factors such as common eating habits, exercise and shared living conditions.

Scientists have been trying to tackle the so-called “missing heritability” problem for nearly a decade, as the inherited nature of conditions such as obesity and diabetes cannot be only attributed to genetic variations.

The Edinburgh University team examined 12 common diseases including heart disease, stroke, diabetes, Alzheimer’s e and four types of cancer, where they looked at the medical histories of 500,000 people from the UK Biobank study.

Shared eating habits and living spaces could be missing link, researchers say. Picture: Getty Images

Using both blood and adoptive relatives, researchers were able to compare how family history of disease appeared with people who were not related by blood, such as husbands and wives, and parents and adoptive children, according to the study published in Nature Genetics journal.

Professor Chris Haley, biomedical genomics programme leader at Edinburgh University’s MRC Human Genetics Unit, said: “The huge UK Biobank study allowed us to obtain very precise estimates of the role of genetics in these important diseases.

“It also identified those diseases where the shared family environment is important, such as heart disease, hypertension and depression, and also equally interestingly those where family environment is of limited or no apparent importance, such as dementia, stroke and Parkinson’s disease.”

Experts say their findings will help to provide a more reasonable idea of how valuable genetic testing can be for identifying people at risk of certain diseases.

The research also underlines the need to identify environmental factors that contribute to diseases and how they can be modified to reduce people’s risk of developing disease.

Prof Haley added: “We must keep looking at genetics which could help us with many things, such as finding potential drug treatments. But we should also look at how we can target environmental factors and how we can get people to change their lifestyles.”