Many dog breeds are purely about appearance—think poodles and the Pekingese. But plenty of other breeds are devoted to specific tasks, like racing greyhounds. For many of these tasks, physical appearance isn’t enough: behavior also matters. Things like herding by sheepdog breeds or fetching by various retrievers.

It’s not surprising that many people ascribe these behaviors—and a wide variety of other, less useful ones—to their dog’s breed and its underlying genetics. Now, a large team of US-based researchers has looked into whether this belief is accurate. And, with a few exceptions, they find that it’s not. With a huge panel of volunteer dog owners, they show that the genetics of dog behavior is built from lots of small, weak influences, and every breed seems to have some members that just don’t behave as we expect.

Dogs, meet Darwin

The work is based on a citizen science project called Darwin’s Ark. Participants were asked to give details about their dog, including whether it belonged to an established breed (either certified or inferred). They were also asked to fill out short surveys that collectively asked about 117 different behaviors. Overall, they obtained data on some 18,000 dogs, about half of them from purebreds.