Looking for a Well-Behaved Dog? Breed May Not Tell You Much.

Americans have as many stereotypes about dogs as there are distinct breeds: Chihuahuas are nervous; border collies are hyperactive; golden retrievers are great with children; and, most infamous, some large breeds — like the American pit bull terrier and Rottweiler — are aggressive.

But a research paper published Thursday by scientists studying the link between genetics and dog behavior suggests that our preconceived notions may be wrong.

Breed means very little in predicting the behavior and personality of an individual dog, the researchers found. That appears to be especially true for traits that are most commonly associated with a dog’s personality, qualities such as cuddliness, friendliness toward strangers and aggression.

“What the dog looks like is not really going to tell you what the dog acts like,” said Marjie Alonso, a co-author of the study and the executive director of the IAABC Foundation, the charitable arm of the International Association of Animal Behavior Consultants.

The study, published in Science, looked at the genes of more than 2,000 dogs paired with 200,000 survey answers from dog owners about their pets’ behaviors. The researchers examined data only on dogs that live primarily as companion animals and did not study how genes influence working dogs bred to perform specific tasks.

Breed accounted for only about 9 percent of behavioral variation in individual dogs and no trait was unique to a single breed of dog, the study found. The researchers speculate that much of the rest of the differences between dogs comes down to individual experiences, training and other environmental factors.

“We do think nearly all the traits are influenced by both genetics and environment,” said Elinor Karlsson, a study author and a professor at the University of Massachusetts Chan Medical School and the Broad Institute.

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“We knew what we were finding wasn’t lining up with people’s stereotypes and what they feel is their lived experience with dogs,” Karlsson said.

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Some traits were more likely to be associated with certain breeds — but those largely had to do with functional behaviors such as howling, pointing, retrieving, herding and playing with toys. On average, beagles and bloodhounds are more likely to howl. German shorthaired pointers are more likely to point. Herding breeds tended to be more biddable — or easily trained — and played with toys more than other breeds. And, predictably, breeds classified as retrievers had a greater propensity to retrieve than other types of dogs.

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