Ask anyone on the street whether they're a cat or a dog person, and chances are, they've got a quick answer. Like the choice between Coke or Pepsi, or chocolate or vanilla, how you respond to cats versus dogs could say a lot about you.
"Dog people are a little more outgoing," a dog owner at the Westminster Dog Show told ABC News. "Cat people are a little more aloof, because that's just how cats are."
Karen Hessel, the proud "mama" to 3-year-old Ripley, a golden retriever, said, "They say that cats are very intelligent but I haven't seen that yet in a cat, but I know my dog is brilliant."
Over at the Black Diamond Cat Show in Kimberton, Pa., cat owners were telling a different story, saying intelligence is the key difference between dog and cat owners. Cat people, they say, are simply smarter.
"Cats are more independent and so are their owners," Martha Auspitz said.
She has been showing cats for nearly 40 years and even met her husband, Norman, at a cat show.
"I was into Abyssinians," he said, "and when I saw Martha's Abyssinians, I knew I needed them and when I saw Martha, I said, 'Oh.' So, in 1982 we were married."
According to the American Pet Products Association, 62 percent of U.S. households have a pet. Dogs win in the popularity race, with 39 percent of U.S. households owning at least one dog, compared with 33 percent of U.S. households owning at least one cat.
The nature of why people prefer cats or dogs is a topic that has been getting increased research in recent years. Scientists at major academic institutions have devoted time and resources to understanding why people become one or the other.
On a practical level, research shows that we tend to gravitate toward the animal with which we were raised. Another big factor is living space and age. Apartment dwellers in urban areas are more likely to have cats or small dogs, while families living in the suburbs are more apt to have larger dogs like retrievers or bull mastiffs.
Parents with young children generally have energetic dogs the kids can play with outside, while single people or older people are more inclined to have the more low-key cat.
Whether you're a cat or dog person is often an accident of geography.
"If you were born in Saudi Arabia, you're more likely to be a cat person," said Harold Herzog, an anthrozoologist studying human-animal relationships at Western Carolina University in Cullowhee, N.C. "Dogs there are very rarely pets because they're considered vermin."
Going deeper than geography or our upbringing, though, scientists believe the selection of species can say a lot about people. A major study at the University of Texas shows that there really is a difference between "dog people" and "cat people."
Those who define themselves as "dog people" are more extroverted, more agreeable and more conscientious than self-described "cat people." Those who love felines, though, were found to be less traditional, more creative and more neurotic.
Dr. Stephen Zawistowski, a science adviser with the American Society for the Prevention of Cruelty to Animals, said research tends to fall in line with the stereotypes people have already established for themselves.
"We think of dog people as being the guy at the beach, with his Labrador [retriever], and throwing the Frisbee and talking to everybody; and the cat lady who sits in her apartment alone with her cats," he said.
Back at the Westminster dog show, men who like cats were getting special distinction by the dog-owners.
"Some guys like to hang out with the guys and then there are the guys that are the loners, you know," Bob Stephanos said. "I bet you the loners are going to be cat guys."
But a quick look of famous pet-owners shows a lot of cat-loving macho men. Ernest Hemingway had a six-toed cat named Snowball. Winston Churchill's cat Jock was one of his favorite pets, often sitting on his knee. Bill Clinton brought his adopted stray cat Socks with him when he moved to the White House in 1992. And in the movies, there's Don Corleone and Dr. Evil.
But for even more support, there's Jackson Galaxy, a 6-foot-2, 275-pound tattooed, guitar-playing dude with a weakness for cats.
Jackson said that cats are the perfectly designed killing machine. Recognizing cats as one of nature's perfect predators is key, and caters to the masculine.
Jackson loves cats so much that he became a professional cat behaviorist. He now stars on the Animal Planet show "My Cat From Hell," where he transforms demonic felines into purring lap cats.
So, is it possible to love both cats and dogs? The obvious answer is -- yes, of course it's possible -- and it even has a name.
"We have to stop this ridiculousness of classifying ourselves," said Jackson, who has a dog in addition to his three cats. "I'm a cat guy, I'm a dog guy. I'm 'bi-petual.'"
Watch the full story on "Pet Crazy" on "20/20" tonight at 10 ET.