“Westminster. There’s only one.” That’s the slogan for America’s most prestigious dog show. Yet despite all the distinctive dog coats that will trot through Madison Square Garden this February, when it comes to the genes responsible, there are only three.

Researchers at laboratories including the National Institutes of Health and the University of Utah have linked ninety-five percent of dog coat variations to these few simple genes.

“Each of our 161 recognized breeds has what’s called a standard, including coat, that describes what an ideal specimen should look like,” says Lisa Peterson, a representative of the American Kennel Club, the governing body for Westminster. For the Portuguese water dog, that standard includes two coat varieties: curly and wavy. “It’s in bold,” says Peterson, reading the judging criteria, “no preference will be given to coat type.”

But for Kevin Chase, a researcher at the University of Utah and coauthor of the study, the Portuguese water dog’s curly-wavy divide proved crucial. Chase describes the two coats as distinct “snapshots” of the dog’s genome. By comparing these snapshots, his team quickly narrowed the cause of this complex trait to the underlying genes.

As researchers now use similar techniques to study genetic causes of dog diseases, they may uncover links applicable to human health. “Dogs and humans have a lot of the same genes,” says Chase. “The purebred dog is an enormously valuable genetic resource.”

None of this is news for Peterson, who is well aware of the scientific importance of AKC breeds: “They have a wonderful gene pool to work from.”