A dog’s breed does not determine its behavior.

A genetic study of over 2,000 dogs, coupled with 200,000 responses from dog owners to related surveys, suggests that breed alone is a poor predictor of behavior.

The results, published in the April 29 issue of Sciencechallenge current assumptions about dog breed stereotypes – notions used to explain why some breeds are more aggressive, obedient or affectionate than others.

According to the results, breed explains less than 10% of behavioral variation in individual dogs; for some behavioral traits and survey items, dog age or sex were the strongest predictors of behavior. Investigators have failed to find behaviors exclusive to any particular breed.

Despite being one of man’s oldest animal companions, nearly all modern dog breeds weren’t invented until about 200 years ago. Before that time – more than 2,000 years ago – dogs were primarily bred for traits essential to their functional roles, such as hunting, guarding or herding. It wasn’t until the 1800s that humans began selecting dogs for their breed-defining physical and aesthetic traits.

Today, most modern dog breeds are assigned characteristic temperaments associated with their ancestral function. As such, the breed ancestry of individual dogs is believed to be predictive of temperament and behavior. This has led, among other results, to a variety of breed-specific legislation, which can include insurance restrictions or outright bans on owning certain breeds of dogs.

Despite these widely held assumptions, there is a distinct lack of genetic research illustrating a link between race and behavior. To solve this problem, Kathleen Morrill, a graduate student at the Broad Institute and Chan Medical School, and her colleagues used genome-wide association studies to search for common genetic variations that might predict specific behavioral traits. in 2,155 purebred and mixed breed dogs. They combined this data with 18,385 surveys of pet owners from Darwin’s Ark, an open-source database of owner-reported canine traits and behaviors.

Behavioral data was analyzed across breeds reported by owners and genetically detected ancestors. The results of these tests, which included data from 78 breeds, identified 11 genetic loci strongly associated with behavior, although none of them were breed-specific.

Among the behaviors most strongly predicted by genetics was dogs’ bidding ability – the way dogs respond to human direction. However, this too varied greatly from dog to dog. Other behaviors, like aggression — a trait unfairly tied to some breeds, like pit bulls — have more to do with the environment a dog is raised in than their genes.