There’s an old adage that says people and their dogs eventually start to look alike. But new research shows the type of dog we choose actually has a lot to with how well they match our own personalities, too.

In work done at the University of Leicester in the UK, lead researcher Vincent Egan found people with aggressive dogs tend to have “low agreeableness” and are “less concerned with the needs of others” and “quicker to become hostile.”

In other words … well, they’re kind of jerks.

That said, researchers didn’t find that people who prefer aggressive dogs are any more likely to engage in delinquent behavior, nor do they tend to have mean dogs as status symbols.

So what qualifies as a “mean dog”? Researchers rated pit bulls and boxers at the top of the aggression scale, and cocker spaniels at the bottom. But those who liked the more stereotypically-vicious dogs weren’t always unpleasant people.

“We were surprised to find a small association between a preference for aggressive dogs and greater conscientiousness (i.e., valuing and following rules),” Egan said. “However, dogs also prefer rules and firm boundaries themselves. We speculate that cheap dog-training classes would be enjoyable and beneficial for both dog and owner.”

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