It doesn’t take a scientist to tell you that golden retrievers are usually friendly and that you shouldn’t aggravate a pit bull. There are exceptions, of course, but the personality types associated with different dog breeds generally hold true. Now, an unprecedented analysis of 17,000 dogs confirms why it’s so consistent: Much of their personality is actually written in their DNA.

"Dog owners are never working with a ‘blank slate’.

The co-lead author of the bioRxiv preprint, Evan MacLean, Ph.D., is a comparative psychologist at the University of Arizona in Tucson and the owner of two dogs with big personalities, a Labrador retriever (friendly, active, outgoing, according to the American Kennel Club), and a Yorkshire terrier (affectionate, sprightly, tomboyish). In the study, also led by Noah Snyder-Mackler, Ph.D., an assistant professor at the University of Washington, the team compared the personalities of 17,000 dogs of different breeds with the genomes of around 5,700 dogs to find a relationship between DNA and their traits. They found multiple: 131 sections of dog DNA that line up with 14 personality traits, across breeds.

“Our findings suggest that there are certainly genetic influences on dog behavior, and dog owners are never working with a ‘blank slate’,” MacLean tells Inverse.

"Excitability" and "energy level" are some of the traits rooted in a dog's DNA. Unsplash / Jamie Street

What makes the study different from previous research on dog personalities is that it examines how dog genomes and personality traits vary across breeds rather than within a breed. Doing so, he says, is a better indicator of the “heritability” of a trait — a measure of how well differences in a dog’s genes accounts for differences in its traits. Just as you wouldn’t study the genetics of eye color in a family of purely brown-eyed people, it doesn’t make sense to study the genetics of dog behavior among similarly behaved dogs of the same breed. Better to study different breeds, so you can see how much of a role genes play in behavior.

The personality “traits,” or dog behaviors, that the team focused on were determined by the C-BARQ (Canine Behavioral Assessment & Research Questionnaire) project, which compiles personality data from about 50,000 dogs of 300 different breeds and cross-breeds, as described by their owners. The 14 traits aren’t quite like the American Kennel Club’s descriptive adjectives; rather, they break those descriptors down into traits shared among dogs.

In the analysis of the 14 traits, trainability, chasing, and aggression seemed to be the most heritable — that is, they were most embedded in differences in the dog genome across breeds. The other traits have to do with dog rivalry; fear of strangers, settings, and other dogs; attachment and attention-seeking; touch sensitivity; and energy level.

MacLean points out that there are no genes specifically for any of these traits; only genes related to these behaviors. “Dogs faced natural problems that required learning, protective behaviors and predatory behaviors etc. long before humans were trying to sculpt any of those traits,” he says. “Natural variance in these types of behaviors may have provided the raw material for breeders to work with in developing dog breeds for more specific functions.”

Some breeds, like shiba inus, are more prone to chasing than others. Unsplash / Jae Lee

"Certain breeds are more inclined to engage in certain behaviors, which can be frustrating if it’s a behavior the owner is struggling with.

Unfortunately for owners who can’t deal with their pet’s personality, this means that sometimes, there’s not much you can do to change how a pet behaves. “Certain breeds are more inclined to engage in certain behaviors, which can be frustrating if it’s a behavior the owner is struggling with,” MacLean says.

That said, even though the analysis shows that certain personality traits are rooted in the genomes of individual breeds, he adds it’s “a mistake to overlook the enormous amount of variation within breeds as well.” As the occasionally aggressive golden retriever and docile pit bull illustrates, genes aren’t everything. “While one breed may exhibit more or less of a particular behavior on average, you never know exactly what you are going to get in any individual dog — you only know, on average, what you might expect to get,” he says.

“So, if you are looking for a dog that has particular characteristics, you can make an educated guess based on breed, but it’s never a guarantee.”

At the end of the day, there will be differences in the inherited behavioral differences among breeds, but MacLean doesn’t think this means that some good boys and girls are better than others. “Different dogs will do different things,” he says, “but to me, thats one of the great marvels and joys of having such an interesting and diverse species to share our lives with.”