Last fall, a 77-pound dachshund named Obie visited the Today show for a spot on pet obesity. “No doubt,” a veterinarian announced to Al Roker as they stood over the table where Obie lay splayed like a pork loin, “this is the biggest dachshund I’ve ever seen.” Roker wondered aloud whether the biggest dachshund might be part of a bigger problem: “Is there a correlation between overweight pet owners and overweight pets?”

Plenty of research has established that pets are good for our health; less is known about whether we might be bad for theirs. But Roker may be on to something. According to one recent study, as U.S. obesity rates shot up over the past half century, the average weight of animals living among humans also increased [1]. Another study linked pet owners’ body mass indexes to their dogs’ fat accumulation [2], backing up a 1970 survey that found that obese dogs were much more likely to be owned by obese people than by those “of normal physique” [3].

Could there be something to the old adage that people resemble their pets? The phenomenon has been amply documented. Researchers around the world have repeatedly found that strangers can match photos of dogs with photos of their owners at a rate well above chance [4]. Perhaps people are drawn to animals that look like them. In a study of female college students, those with longer hair judged flop-eared dogs—spaniels, beagles—to be more attractive, friendly, and intelligent than dogs with pointy ears; women with shorter hair concluded the opposite [5]. And the apparent affinity between owners and pets is more than fur-deep: One analysis found self-described “dog people” to be less neurotic than “cat people,” who were more curious [6]. Another study, which cross-referenced personality-test scores and breed preferences, noted that disagreeable people favored aggressive dogs [7].