Thousands of people in the UK are likely to be the result of “extreme inbreeding” between close relatives, a study has suggested.
An analysis of DNA stored in the UK Biobank, which stores hundreds of thousands of volunteers’ genetic material, found a fraction of those sequenced were conceived by parents who are either first or second-degree relatives.
A first-degree relative is someone who shares 50 per cent of a person’s genes, so a parent or child, while second-degree relatives are those who share 25 per cent of the same DNA, including uncles, grandparents and half-siblings.
Of a total of more than 450,000 participants, researchers from the University of Queensland found 125 whose genes suggested they were the offspring of extreme inbreeding.
The volunteers were all individuals of European descent born between 1938 and 1967.
Extrapolating the sample data across England and Wales results in an estimate of 13,200 people born to inbreeding, but the study’s authors warned the figure could be even higher.
“The extent to which our estimate reflects the true prevalence of [extreme inbreeding] in the entire UK population is a difficult question,” the researchers said in a statement to the Daily Mail.
“The UK Biobank is known to have over-representation from healthy and highly educated individuals, which likely biases our estimates.
“Highly inbred individuals who suffer severe health consequences may be less likely to participate in a study such as the UK Biobank.
“Therefore, our estimate of the prevalence might be too low.”
The study, led by Dr Loic Yengo and published in Nature Communications, outlines the many health consequences for children born to incest, including increased chances of low fertility, stunted growth and lifespan, poor lung function and reduced cognitive ability.
To determine whether an individual was conceived through inbreeding, the researchers looked for abnormally high incidences of DNA sections identical to each other, known as homozygosity.
According to the American College of Medical Genetics, DNA which features 10 per cent or more homozygosity is suspected to be the result of the same genetic code being inherited from the mother and father.
The researchers have been contacted for comment.