Your Roommate Could Be Changing Your Genes, Researchers Say

A roommate can do more than pay for their share of the bills – they can also influence your health, according to a new study.

Researchers from the European Molecular Biology Laboratory conducted a study that quantified social genetic effects (SGE) in laboratory mice. For example, a mouse sharing a cage with another mouse can be affected in several ways.

The authors said that social genetic effects can even be studied when the traits that mediate the influence of the social environment aren’t known. Co-author Amelie Baud, a postdoctoral fellow at the European Bioinformatics Institute in Hinxton, England, said SGE shouldn’t be ignored.

“The take-away message here is that we need to pay attention to the genetic makeup of social partners, since in some cases it affects health more than the individual’s own genes,” Baud said. “This is something we did not know before. It means we need to stop looking at individuals in isolation and include social partners when we look at an individual’s health.”

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Over 40 traits in the mice were believed to be influenced by their neighbors. The mouse’s rate of growth, lung function and even blood biochemistry were just some of the traits changed by the cage mates.

The study said that genetic variation in cage mates can explain up to 29 percent of the variation in anxiety, wound healing, immune function and body weight. The authors also stated that ignoring SGE can severely bias estimates of direct genetic effects, which can have important implications for a study of genetic basis of complex traits.

Baud said the research “could inform patients and doctors on social contributions to disease and provide clues as to how to mitigate social influence, or indeed enhance it when it has beneficial effects.”

The genetic changes in the laboratory mice weren’t always straightforward during the study. Black mice sharing spaces with gray mice were able to heal better than when they were with other black mice. Gray mice had less anxiety when sharing a cage with black mice instead of other gray mice. No one type of mouse had positive or negative effects on traits across the board when it came to cage mates.

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For humans, Baud said an example of social genetic effects could show up in partners with different sleeping habits. A night owl’s genetics, or tendency to stay up later, could alter a morning person’s genetics, leading to health issues, she said.

The study said the influence of the social environment was “unexpectedly large.” Though the study was conducted on mice, the study could mean more for the world of genetics, the authors wrote.

“Our study sheds light on an important component of the genetic architecture of complex traits, one that lies outside the individual, in social partners,” the authors wrote. “Social genetic effects have already been shown to play an important role in artificial selection of livestock and have important evolutionary consequences. Our results provide evidence that SGE are also an important component of health and disease.”