With their smiling eyes and wagging tails, dogs often make life easier for us. As it turns out, their DNA recently had a similar effect for geneticists. Most of the complex array of coats that dogs wear—from the halo of softness engulfing the Pomeranian and the wiry bristles of a Scottish Terrier to the curls of a spaniel and the sleek jacket of the lab—can be reduced to the influence of just three genes.

The National Human Genome Research Institute in Bethesda, Maryland, headed a study of the coats of over 1,000 dogs from eighty breeds. They noted three traits in each dog: the length of its coat, how curly its coat was, and whether or not it sported the prominent “eyebrows” found on many wiry-haired breeds. Then they hit the labs, analyzing the specific sequence of each dog’s genetic code. When they compared dogs to DNA, they saw that each of the three traits they had observed was governed by its own gene, acting independently from the others. It was the combined influence of the three genes that created the tremendous variation in coats seen among the different breeds.

The researchers may not have been overly surprised to find three genes governing the three traits they looked for, but the results are nonetheless significant; they show that wildly diverse physical features can have relatively simple genetic explanations.

“You can’t understand abnormal until you know normal,” says Kari Walsh, a collaborator on the project, summing up her team’s motivation. They hope that in understanding regular gene function, they’ll be one step closer to understanding genetic diseases—not just in dogs, but in humans as well.