Like most Maine Coons, Dawntreader Texas Calboy is regal: thick tufts of hair fill out his large body, giving him a look that seems more big cat than housecat. His bushy tail, a trademark of the breed, frames his crouching form, lending an imposing look to the gentle giant as he poses on a log near his family’s home in Waxahachie, Texas.

But what truly makes him unique is his coat color. Calico coats are associated with female cats, and for good reason — only one out of every 3,000 Calicos are male, according to a genetic study by a researcher team at the University of Missouri’s College of Veterinary Medicine. And even in that exclusive club, Calboy is unique as an extremely rare fertile male calico, since most of the males who sport the coat color are incapable of reproducing. Only one out of 10,000 male calicos are capable of fathering kittens.

A double-take at the vet

“It wasn’t until we took him for his second week of shots at our vet, that I realized he was a boy, and I was shocked,” said Mistelle Stevenson, a Texas breeder who decided to keep Calboy as a member of her permanent household pride.

So how does a coat color associated almost entirely with female cats end up on a male, and why is the combination so rare?

Calboy is a chimera, according to veterinarian Brittney Barton of HEAL Veterinary Hospital in Dallas.

“Where the question comes in is how on Earth do we get a male cat to express what is known as a predominantly female trait? Because it’s technically almost genetically impossible to get that type of combination,” Barton told the Dallas-area NBC affiliate, NBCDFW.

Chimeras have two sets of DNA, Barton said. Normally, “we have one embryo with two different, separate, fertilization incidents,” which results in non-identical twins, the veterinarian explained.

“Where a chimera comes in,” Barton said, “that’s when non-identical twins merge.”

How XX becomes XXY

Male cats have X and Y chromosomes, while female cats have two X chromosomes. The X chromosome is responsible for coat color: With only one X, males can be either orange or black, but normally not both. But with two X chromosomes, females can be orange and black.

A chimera like Calboy has three chromosomes — XXY — which is caused by an incomplete division of the male’s XY chromosome pair at the time of fertilization, according to the University of Miami. The unusual combination allows a cat like Calboy to develop a coat pattern and color combination that would be normally impossible for males.

It’s usually at this point when some people get confused: “Wait, but isn’t Calboy a Maine Coon? How can he be a Maine Coon and a Calico?”

Just like a wide variety of cat breeds — including Siamese and domestic short-hairs — can be tabby cats, as many as 16 different breeds can be calicos. That’s because tabby, calico and tortoiseshell are coat patterns, not breeds.

The Cat Fancier’s Association doesn’t fancy him

As for Dawntreader Texas Calboy, while he’s got a loving family and a long life of being adored by his humans ahead of him, one thing he won’t be doing is winning awards for “best in breed” at cat shows.

The handsome calico made his debut in January at a Houston show sponsored by the Cat Fancier’s Association (CFA), but despite universal agreement that Calboy has the looks, he’s barred from appearing in any future CFA “best in breed” events.

The judges “were holding him up and talking about how well he met the standard and how beautiful he was, and then they would say ‘well, if he was a girl,’ because his color was allowed as a girl, ‘if he was a girl we would final him, I might even make him best in show,'” Stevenson said.

The CFA added the matter of Dawntreader Texas Calboy to its February 2018 board meeting as an emergency addendum, voting to explicitly bar chimeras from cat fancy shows. In a statement provided to NBA, the CFA said it’s concerned chimerism, which is a genetic anomaly, could be detrimental to cats.

However, Calboy — and other chimeras like him — can still compete in the household pet and agility categories, according to the CFA, and the International Cat Association, a separate organization, hasn’t put any restrictions on chimeras.

“In a perfect world, I would just like for them to just look at him as the cat, and does he meet our standard or doesn’t he meet it, and this is the coat color, and it happened naturally on him,” Stevenson said. “It’s not his fault he was born a boy and not a girl.”

Cover image Dawntreader Texas Calboy  by Mistelle Stevenson Courtesy