Do your genes determine who you date?

What if the thing that really made you fall for your other half wasn’t actually that dazzling smile, beautiful body or irresistible charm? Many studies have shown that apart from socio-cultural influences, there are also biological factors involved in your choice of partner. Analysis of the genetic data of couples has revealed that the reasons for getting together can be down to your genes... An evolutionary theory even if it isn’t very romantic!

You’ve got lovely... genes

A recent study led by researchers at the National Museum of Natural History and the CNRS has shown that it is possible to tackle the question of how we choose each other by looking at our genetic codes. The results of the study were published recently in the Molecular Ecology journal.

It has been known for a long time that biological factors play a role in choice of partner for the human race, in the same way as socio-cultural influences. In this study, it was observed that in terms of some key physical characteristics, like size for example, people tended to choose someone who was similar to them. On the other hand, when it came to the functions of the immune system (especially the Major Histocomptability Complex or MHC genes which control the body’s natural defences), the results indicated that individuals choose partners who have different genes to them. This strategy could allow people to ensure their children are born with greater resistance to infection.

When culture meets genes

Nowadays, there are analytical tests designed to work out the genetic compatibility of couples, like the HapMap project which allows exploration of the possible reasons for choosing each other according to many different genes. Romain Laurent’s team along with collaborating partners, Raphaëlle Chaix and Bruno Toupance, have analysed more than a million genetic markers taken from close to 20,000 genes. Analyses were carried out on couples with African origins (from Yorubas in Nigeria), Americans (Mormons from Utah) and Mexicans (Mexicans living in Los Angeles). For each gene, the researchers tested if married couples were closer or further apart genetically than they would be just by chance, and if the similarities or differences were noticeably extreme in comparison to the rest of the genome.

And the results? Some genes were identified as playing a part in how people choose each other; some were connected to physical appearance like the genes which determine skin pigmentation or body shape, and others were tied to the immune system and genes which determine behaviour. The creators of the study also underlined the “differences shown between populations which indicate that biological factors involved in the choice of partner are largely influenced by culture.” More simply, certain cultures will value certain genetic characteristics which have no real interest for the partner at all. This is why it is culture which influences our natural, “biological choices”.

The researchers behind the study have concluded that it is necessary to study more groups of people in order to get a better understanding of the evolutionary forces at work behind our genetic mix.

Sources:

“Non-random mate choice in humans: insights from a genome scan”, by Laurent R. Toupance B. Chaix R. Molecular Ecology 21(3):587-96
Projet HapMap: An international project which aims to map out human genetic diversity. “HapMap” is a partnership between scientists and financial organisations across Canada, China, Japan, Nigeria, the United Kingdom and United States.

David Bême

Posted 16.07.2012

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See more in the dossier: The psychology of relationships