Popular genetics tests can’t tell you much about your dog’s personality, according to a recent study.
A team of geneticists recently found no connection between simple genetic variants and behavioral traits in more than 3,200 dogs, even though previous studies suggested that hundreds of genes might predict aspects of a dog’s behavior and personality. That’s despite the popularity of at-home genetic tests that claim they can tell you whether your dog’s genes contain the recipe for anxiety or a fondness for cuddles.
Gattaca for dogs, except it doesn’t work
University of Massachusetts genomicist Kathryn Lord and her colleagues compared DNA sequences and behavioral surveys from more than 3,000 dogs whose humans had enrolled them in the Darwin’s Ark project (and filled out the surveys). “Genetic tests for behavioral and personality traits in dogs are now being marketed to pet owners, but their predictive accuracy has not been validated,” wrote Lord and her colleagues in their recent paper.
So the team checked for relatively straightforward associations between genetic variants and personality traits such as aggression, drive, and affection. The 151 genetic variants in question all involved small changes to a single nucleotide, or “letter,” in a gene, known as single-nucleotide polymorphisms (SNPs).
It turns out that the answer was no: Your dog’s genes don’t predict its behavior, at least not in the simplistic way popular doggy DNA tests often claim.
And that can have serious consequences when pet owners, shelter workers, or animal rescues use these tests to make decisions about a dog’s future. “For example, if a dog is labeled as genetically predisposed to aggression, an owner might limit essential social interactions, or a shelter might decide against adoption,” Lord and her colleagues wrote.
Why does your dog do that weird thing? It’s complicated
There probably is some genetic component to certain aspects of dog behavior; otherwise, breeders wouldn’t have had so much success at crafting working dog bloodlines with a propensity for things like intelligence or herding drive. But it’s a lot more complicated than something like “we found the gene behind zoomies,” for example—which is a pity for those of us who love simple answers and want to understand our pets better.
For starters, most behavioral traits are polygenic, which means that they’re the result of complex interactions among multiple genes, which may be spread across different chromosomes. It’s possible to tease out those connections, but it’s going to take exponentially more data than any dog genetic study has gathered so far. Darwin’s Ark is among the largest to date, with its 3,287 dogs, but Lord and her colleagues say it could take a sample of tens of thousands, or even hundreds of thousands, of dogs to find useful answers about the genetics of canine behavior.
Making matters even more complicated, less than half of any given doggy personality trait is actually down to genetics; for some traits, it’s as little as 8 percent. The rest is shaped by environmental factors—that complex mix of experience, training, and social learning. Environmental factors are so important that, as Lord and her colleagues put it, they can “limit the potential accuracy of genomic predictions.”
All of that means that a genetic test can tell us why your faithful correspondent’s dog has gray fur, but probably not why he barks until he’s been greeted properly.
False paw-sitives (we are not sorry)
Previous studies have found links between particular SNPs—including some of the 151 in Lord and her colleagues’ recent study—and dog behavioral traits. Lord and her colleagues say many of those associations may actually be false positives.
As mentioned, dog genetics doesn’t have the huge sample populations that human genetic studies often work with, and most of the genetic sequences that are available aren’t accompanied by detailed behavioral information about that particular dog, which makes it difficult to get statistically useful results. One way that some studies try to get around this is something called breed-average studies. In a breed-average study, the researchers assign a behavioral phenotype to every dog based on their breed’s average score on a behavioral test.
This can work well enough for physical traits, which vary relatively little between dog breeds (one dachshund looks much more like the next dachshund than it does a dalmatian). But personality traits vary as much within breeds as between them, which means breed-average behavioral scores aren’t very useful. As Lord and her colleagues put it, “averaging phenotypes by breed and then testing for genetic predictions is inherently circular.”
The result is often that breed-average studies find things that look like connections between an SNP and a behavioral trait, when in reality, that SNP just happens to be located alongside the gene for a physical trait like fur color or ear shape. If that physical trait is common to a particular breed, then the SNP that’s tagging along with it in the genome will look like it’s linked to the breed-average behavioral score for that trait—even if it’s not.
And, in this latest study, “not” seemed a lot more likely. “We did not replicate any of the associations reported in the breed average studies,” Lord and her colleagues wrote.
PNAS, 2025. DOI: 10.1073/pnas.2421752122 (About DOIs).
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