Are all calico cats female? Calico cats have black, orange, and white coats. They are not a single breed, in fact many different cat breeds can be calico.
Thanks to their genetics, most calico cats are female. But, very occasionally male kittens can be born with a genetic anomaly that makes calico coloring possible.
Let’s take a closer look at the question: are calico cats always female?
Are Calico Cats Always Female?
The vast majority of calico cats are female because of the way coat color is inherited from their parents and stored on their DNA.
Cats’ DNA is stored on thirty eight chromosomes arranged in nineteen pairs. In each pair, cats inherit one chromosome from their mom, and the other from their dad.
Just one pair of chromosomes determines whether your cat is a girl or a boy (actually this is true of all placental mammals, and you!)
The sex chromosomes are pair number nineteen, and they come in two forms: X and Y.
Now, the X chromosome isn’t just important for determining sex, it has lots of important genetic information on it, including genes which control coat color.
We will take a closer look at exactly how and why are calico cats female further in this article. But, for now, you can see at least why coat color and gender are linked!
What is a Calico Cat?
Before we get stuck into genetics and the question of ‘why are calico cats female’, let’s be clear which cats we’re talking about.
Calico cats have three colors in their coat. The first two are black and orange like a tortoiseshell, and the third is white.
Sometimes the black or orange patches contain a tabby stripe and these cats are occasionally known as calibies.
Every calico cat has her own unique medley of black, orange and white splodges in different proportions, and their endearing patchwork appearance has made them popular all over the world.
In Japan they’re believed to bring good luck, and they’re even the state cat of Maryland!
Difference Between Calicos and Tortoiseshells
Tortoiseshell cats (often affectionately known as torties) only have two colors in their coat.
By convention we call these colors black and orange. But black can mean jet black, or smoky coal, chocolatey brown, and even silvery grey or blue.
And orange can mean anything from deep russet or vibrant ginger through to soft fawn and delicate cream.
The two colors appear in a mottled pattern, which could take the form of big splotches or smaller speckles.
One of the colors can even have a tabby stripe within it, and these cats are sometimes called torbies!
Which Breeds Can Be Calico?
Calico cats aren’t their own individual breed. Here are some cat breeds that can have the beautiful calico coloring:
- Manx cats
- Norwegian Forest cats
- Bobtail cats
- American and British Shorthair
- Maine Coon
- Turkish Van
- Turkish Angora
And more! Now back to the original question: are all calicos female?
Why Are So Many Calico Cats Female?
As we know, the chromosomes that determine a cat’s gender are called X and Y. A cat with two X chromosomes is a girl, and a cat with an X and a Y chromosome is a boy.
And, as we learnt earlier, the X chromosome is also responsible for traits like coat color.
Male cats only have one X chromosome, which means they only receive one set of genes to decide coat color.
But female cats have two X chromosomes, which means they receive two sets of genes with instructions about coat color.
How We Get To Calico
Now it starts to get amazing. To manage these two sets of genetic information, whilst female kittens are still tiny embryos, each cell deactivates one of their X chromosomes.
So what if the female kitten has inherited different coat color instructions from each parent, for example “be black!” from their mum and “be orange!” from their dad?
Well, in each cell one set of instructions will be silenced, but it which one is completely random, and the cells don’t swap notes, they don’t all silence the same instruction.
So some cells keep the instruction to make black fur, and some keep the instruction to make orange fur.
And the result? A beautiful mottled tortoiseshell!
But That’s Still Not Calico!
That still doesn’t answer our question: are all calicos female, because tortoiseshells are missing one of the three calico colors!
Calico cats are fundamentally tortoiseshell cats, but with an extra layer of genetic instructions.
As well as the same gene expression giving them a mottled black and ginger appearance, they also have the White Spotting gene, which layers white spots over the top of the black and orange pattern.
So calico cats are always female because underneath the white patches they are tortoiseshells.
And tortoiseshells are always female because only female cats have two X chromosomes and carry two sets of instructions about coat color.
Male cats cannot usually be tortoiseshell or calico because they only have one X chromosome, which means they can only carry genes for orange or black fur, not both. Take a closer look at male ginger cats in this guide.
So, to summarise – calico cats are female because their two X chromosomes make it possible!
How Do Male Calicos Occur?
Are all calico cats female? No! Whilst the majority of calico cats are necessarily female, very occasionally male kittens are born with a genetic anomaly which makes it possible for them to have calico coloring.
The anomaly is called XXY Syndrome, and as you can guess from the name, it occurs when a male kitten inherits two copies of the X chromosome AND a Y chromosome.
Male calico cats are rare – a widely accepted figure is that only 1 in every 3000 calico cats are male. It’s not clear where this figure comes from though, or how accurate it is. In humans, between 1 in 500 and 1 in 1000 baby boys are born with XXY chromosomes (called Klinefelter Syndrome).
The rarity of male calico cats has given rise to the rather mercenary myth that they are especially valuable too. However this is not the case.
Unless he is a pedigree – in which case his value will come from being a pedigree – he has no more value than any other moggy (notwithstanding that all our beloved pets are priceless, of course!)
Why Aren’t Males More Valuable?
The main reason for this is that inheriting the XXY combination of chromosomes almost always leaves male calico cats sterile.
So they don’t have any special value for breeding more calico kittens.
However, like everything else in this life, male tortoiseshell and calico cats are worth whatever someone is willing to pay for them.
So if someone has their heart set on owning a calico male, you might hear stories of them paying over the odds to get one.
Are All Calico Cats Female? A Summary
So the answer to our original question “are calico cats always female” is almost. But there are exceptions!
Do you have a tortoiseshell or calico cat? What breed are they? And are any of them boys? Tell us if you’ve ever met a male tortoiseshell or male calico in the comments section.
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References and Resources
- Ghose, T., ‘Genetic Process Behind Calico Coats Visualized’, Live Science (2014)
- Robinson, R., ‘Genetics for Cat Breeders and Veterinarians’, Butterworth-Heinemann Medical (1991)
- Travis, J. ‘Silence of the Xs’, Science News (2000)
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