40 Pets With Unique Genes That Have Given Them Really Distinctive Looks

One of the most frequent congenital physical anomalies we see in this list is polydactylism, which causes animals to be born with more than the usual number of toes on one or more of their paws.

Interestingly, the condition seems to be especially common in cats along the East Coast of North America (in the United States and Canada and in South West England, Wales, and Kingston-upon-Hull.

Polydactyl cats have been extremely popular as ship's cats as well. Even though there is some controversy over the question of whether the most common variant of the trait originated as a mutation in New England or was brought there from Britain, there seems to be agreement that it spread widely as a result of cats carried on ships originating in Boston, Massachusetts, and the prevalence of polydactyly among the cat population of various ports correlates with the dates when they first established trade with Boston.

Sailors have been known to value polydactyl cats especially for their extraordinary climbing and hunting abilities as an aid in controlling shipboard rodents. Some even thought they bring good luck at sea. The rarity of polydactyl cats in Europe might be explained by the fact that they were hunted and killed due to superstitions about witchcraft.

The legendary Nobel Prize-winning author Ernest Hemingway was an aficionado of polydactyl cats too. His love for these animals began after one ship captain gave him a six-toed cat he named Snow White.

Upon Hemingway's death in 1961, his former home in Key West, Florida became a museum and a home for his cats, and at one point it housed approximately fifty descendants of his cats (about half of which were polydactyl). Because of his immense love for these animals, polydactyl cats are sometimes referred to as "Hemingway cats".

"The things that make me different are the things that make me," one very special animal said. And the animals in these pics are very special too.