When it comes to choosing a mate, opposites really do attract, according to a Brazilian study that found people are subconsciously more likely to choose a partner whose genetic make-up is different to their own. They found evidence that married couples are more likely to have genetic differences in a DNA region governing the immune system than were randomly matched pairs.
Scientists said it was not clear what signals attract the body to people who are genetically dissimilar to themselves, but suggested body odor or even face structure could play a role. Many researchers have found evidence that animals are attracted to members of the opposite sex with differences in major histocompatibility complex or MHC, an immune system factor that also plays a role in having healthy offspring.The MHC is a large genetic region situated on chromosome 6, and found in most vertebrates. It plays an important role in the immune system and also in reproductive success. Apart from being a large region, it is also an extraordinarily diverse one.
The team compared genetic data from 90 married couples with data from 152 randomly generated control couples. They found the real couples had significantly more dissimilarities in MHC.
"Parents with dissimilar (genetic regions) could provide their offspring with a better chance to ward infections off because their immune system genes are more diverse," they wrote in a summary preparation.
Previous studies have suggested animals may use body odor as a guide to identify possible mates as being genetically similar or dissimilar, she added, but other physical factors may also be involved.
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