Pass the Smelling Salts
It may not be a conscious decision, but a study has found we seek out partners who have a similar genetic ancestry to our own.
Researchers studying children in Mexico and Puerto Rico discovered their parents tended to share similar genes, even though they weren’t related.
In fact, the average mix was so alike in some cases, the couples were as genetically similar as third or fourth cousins. This is known as ‘assortative mating’.
The research was led by Dr Noah Zaitlen from the University of California, San Francisco.
His team specifically studied the parents of Mexican and Puerto Rican children with asthma.
In the case of Mexicans, the parents typically had a similar proportion of mostly European and Native American ancestry, with some genomic heritage from Africa.
For Puerto Ricans, this ‘assortative mating’ meant they had similar amounts of European and African ancestry, with some Native American.
The average mix was similar enough to make the couples equivalent to between third and fourth cousins, said the researchers.
This degree of closeness may have implications for genetic diseases.
In particular, because Puerto Ricans have mutations from both the Spaniards who colonised the island and the Native American women who bore their children, the researchers estimated assortative mating could increase the chances of recessive diseases by two to 14 per cent after 10 generations of mixing.
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