Genes Keep You On A Long Leash With Your Dog

Researchers believe that our genetic make-up has a significant influence on whether we bring a dog into our house or not.

This love has lasted for at least 15,000 years. That’s how long people have lived with dogs. They were the first animals we domesticated. But not everyone wants a four-legged friend by their side. Whether you want to share your life with a dachshund, poodle, or Labrador does not only depend on the experiences you made with these animals in your childhood. Love for dogs is also genetic, according to Swedish and British researchers at Uppsala University and the University of Liverpool (1).

Their study included data from 35,035 monozygotic and dizygotic twins born between 1926 and 1996. The researchers received information on dog keeping from government registries and dog breeding associations (in Sweden, dogs also have to be registered).

Twin studies are a popular method to find out what influences the environment and genes have on human biology and behavior. Since identical (monozygotic) twins have almost their entire genome in common, but fraternal twins only about half, comparisons between groups can show whether genetics plays a role in the ownership of a pet. In fact, dog love was particularly common in monozygotic sibling pairs. If a female twin had a dog, the twin sister was 40% likely to also have a dog. The situation was somewhat different from dizygotic (non-identical) twins: in these twin sets, the co-sister was only 25% likely to also have a dog.

The researchers observed a similar situation with male twins. In twin sets where the male monozygotic twin had a dog, there was a 29 percent probability that his twin brother was also a dog owner. The probability was only 18 percent in the case of dizygotic twins. The question of dog keeping, therefore, has a large genetic component. The scientists calculated that the hereditability of this trait is 57 percent for women and 51 percent for men.

A weak point of the study is that it does not investigate how many of the twins live with a dog that is not registered to them, or not at all, or to their partner. This information could have an effect on the researchers’ figures.

The researchers’ summary is cautious. “Some people are dog people, others are not. And our results suggest that hereditary factors can explain the difference,” says Tove Fall, Professor of Molecular Epidemiology at the University of Uppsala.

The twin study does not allow any conclusions to be drawn as to which genes are affected. The next step will, therefore, be to find out which genetic variants are decisive for a love of dogs and how they affect other health factors.

Again and again, studies suggest that dogs can have a positive effect on the health of their owners, be it in care or in everyday life. Dog owners seem to develop less asthma (2), move more (3) and live longer (4). The question is, why is that? Is it an effect that comes directly from the dog or is it more about dog lovers having other genetic requirements?

Carri Westgarth, a lecturer in human-animal interaction at the University of Liverpool and co-author of the study, says, “These results suggest that the supposed health benefits of owning a dog, which have been reported in some studies, can be explained in part by the different genetics of the individuals studied.”