A family history of disease may be as much the result of shared lifestyle and surroundings as inherited genes, a study says.
Factors that are common to the family environment such as shared living space and common eating habits can make a major contribution to a person's risk of developing a disease, the study found.
The study, published in the journal Nature Genetics, used data from the UK Biobank that recruited 500,000 people aged between 40 and 69 years in 2006-2010 from across the country with the aim of improving the prevention, diagnosis and treatment of a wide range of serious and life-threatening illnesses.
"The huge UK Biobank study allowed us to obtain very precise estimates of the role of genetics in these important diseases," said Professor Chris Haley, Roslin Institute, University of Edinburgh in Britain.
"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," Haley noted.
Previous studies have identified genes that are linked to numerous medical conditions, yet these only account for part of a person's likelihood of developing a disease.
The new research looked at incidences of 12 common diseases including high blood pressure, heart disease, and several cancers and neurological diseases.
By not accounting for shared environmental factors, scientists may overestimate the importance of genetic variation by an average of 47 per cent, the study found.
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