Summary: A large twin study shows a substantial genetic contribution to adult dog ownership. Researchers suggest that genetic variation may have helped shape human capacity to domesticate dogs and could influence reported health associations with pet ownership.
Source: Uppsala University
Overview: A collaborative team of researchers from Sweden and the United Kingdom examined whether dog ownership is influenced by genetics. Using data from the Swedish Twin Registry covering twins born between 1926 and 1996, the study analyzed 35,035 twin pairs to estimate how much heredity contributes to the likelihood of owning a dog. The results indicate that genetic differences account for more than half of the variation in adult dog ownership, suggesting that the decision to keep a dog is strongly shaped by inherited factors as well as environment.
Dogs were humanity’s first domesticated animal and have shared a close relationship with people for at least 15,000 years. Today dogs are widespread as companion animals and are frequently associated with benefits to owners’ well-being and health. To explore whether the tendency to own a dog has a hereditary basis, the researchers linked national dog register records (2001–2016) with the Swedish Twin Registry—the world’s largest registry of its kind—and applied established twin-study methods to separate genetic and environmental influences.
Tove Fall, lead author and Professor in Molecular Epidemiology at Uppsala University, says the team was surprised by how prominent the genetic contribution appeared. “Our findings show that an individual’s genetic makeup is an important determinant of whether they become a dog owner. This has implications for many fields, from human-animal interaction research to studies of health outcomes related to pet ownership. Some people may simply have a stronger innate inclination to care for animals.”
Carri Westgarth, Lecturer in Human-Animal Interaction at the University of Liverpool and co-author, emphasizes a consequence for health research: “These results suggest that observed health benefits linked to dog ownership in prior studies could be partly influenced by genetic differences among owners.”
Classic twin-study logic underpins the analysis. Identical (monozygotic) twins share virtually all their genes, while fraternal (dizygotic) twins share on average half of their segregating genes. By comparing how often both members of a twin pair own a dog, researchers estimated the relative contributions of additive genetic effects, shared environmental influences, and unique environmental factors. Concordance for dog ownership was notably higher among identical twins than fraternal twins, supporting a large genetic component.
Senior author Patrik Magnusson, Associate Professor in Epidemiology at Karolinska Institutet and Head of the Swedish Twin Registry, notes that twin designs cannot identify specific genes but can robustly estimate the proportion of variation explained by heredity. “We estimated heritability at approximately 57% for females and 51% for males. Shared environmental effects were observed mainly in early adulthood, while unique environmental factors also played an important role,” he explains. The next research step will be to search for particular genetic variants that influence dog ownership and to study links with personality traits, allergies, and other relevant factors.
Keith Dobney, zooarchaeologist and co-author at the University of Liverpool, highlights the evolutionary perspective: “This study offers a new angle on dog domestication. Archaeological and ancient DNA evidence have illuminated where and when dogs entered human societies; our results suggest that genetic variation in humans may also have contributed to the process of domestication by shaping who was likely to keep and care for dogs.”
Source:
Uppsala University
Media contact:
Tove Fall – Uppsala University
Image source:
The image is in the public domain.
Original research (open access):
“Evidence of large genetic influences on dog ownership in the Swedish Twin Registry has implications for understanding domestication and health associations”. Tove Fall, Ralf Kuja-Halkola, Keith Dobney, Carri Westgarth & Patrik K. E. Magnusson. Scientific Reports. DOI: 10.1038/s41598-019-44083-9
Abstract (summary)
This large-scale twin study used national dog registers linked to the Swedish Twin Registry to investigate whether adult dog ownership is heritable. The sample included twins born 1926–1996 and alive in 2006, with dog ownership information available from 2001–2016. The final dataset comprised 85,542 individuals from 50,507 twin pairs, with both twins’ data available for 35,035 pairs. Structural equation modelling was used to estimate additive genetic, shared environmental, and unique environmental contributions. Results indicate strong additive genetic effects on dog ownership, with estimated heritability around 57% in females and 51% in males. Shared environmental effects appeared mainly in early adulthood. These findings suggest that genetic variation has a substantial role in dog ownership and may have implications for understanding domestication and for interpreting associations between dog ownership and health outcomes.