Have you heard rumours that all calico cats are female? Well, although it’s not quite as simple as that, there is some truth to it. As thanks to their genetics, most calico cats really are girls. But, very occasionally male kittens can be born with a genetic anomaly that makes calico coloring possible.
Why Are Calico Cats Normally 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.
Is The Same True For Torties?
Calico cats are often confused with tortoiseshell cats, and both types are often mistaken for being breeds of cats. But, they are types of coloring which can be seen in many different breeds.
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.
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:
- Persians
- 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?
Variations in Color Genetics
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.
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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)
The only Calico & Tortoiseshell cats that I’ve ever had were & are Female! I had a Persian who had a black father and an orange/white mother! Her 2 brothers were orange & white!
The tortie I have now is a mute or buff (gray & pink)!! Although they were opposite in one dark & one light, they were both female!!
Pretty much every cat I’ve ever had has been a calico. I’ve had mostly long-haired dilute calicos, which are my most favorite because their colors of gray, white and butterscotch are just sooo pretty. But I’ve had ‘regular’ (?) calicos, too, which are stunning because their colors can be so bright and shiny. And the fun part about calicos, is that no two are alike. Their patterns and colors are all so different from one another. That’s what makes each one so unique and stunning and beautiful to look at.
Calicos, I believe, are some of the smartest cats you’ll ever come across. They’ve certainly got unique personalities, as all cats do; but as veterinarians and vet techs will tell you, they are a force to be reckoned with! They know what they want and when they want it. And they know when they don’t want something and can be stubborn.
On the other hand, calicos are extremely loving and loyal to “their” people, and are always seeking them out for company. They have a need to be near their people at almost all times. (Again, I’ve have no other type of cat to compare this to. Maybe all cats are like this, I’m not sure. But in my experience, calicos are definitely this way.) Calicos also express their affection with lots of head bunting, talking and ‘chirping’.
You’d be lucky to have a calico love you.
Thanks for your lovely post Kaye – it’s great to hear from a calico cat fan 🙂
I love how you describe a Calico. My mother had one and she was a very little kitty. I loved her because she was so easy to love. When I went outside during the winter wearing a heavy coat, mom’s little kitty wanted under my coat. My mom passed away so my brother took her since my landlord wouldn’t allow pets. Eventually our beautiful little creature came up missing. Saddest thing ever.
I loved your post, about a year ago I took a Calico cat from my friend’s granddaughter due to allergies and now she starting to get more and more close to me but of course on her terms.
Never had this type of cat before but of the various ones I had this one is the smartest of them all.
Hello,
Our cat just brought 3 kittens three weeks ago. One of them is calico, I even didn’t think about the sex, cause I was always thinking that calico are female. So, I was shocked today to learn that our calico kitten is actually a boy!!! And it has pure three colors: white, gray and orange
I had a beautiful calico girl ‘Foamy’ some years ago. Her face was elegantly coloured half black, half orange, with a white nose, though both eyes were green. She was loving and cuddly, VERY good with my babies and moved house with me 13 times. She lived 17 years.
West Australia.
Our lovely cat Milo is white with a ginger tail and some splodges of ginger on his head. His mother was a calico, but father unknown. His fur is extremely thick unlike any cat we’ve ever had! He has a lot of characteristics of a Turkish Van cat! Could that be possible? He has no other colours, just ginger and white? He loves to sit on the side of the bath when you’re in, to watch the water! He has been known to walk around with a stick in his mouth and makes friends with all the cats in the neighbourhood who spend their time sunning themselves together and play fighting! He has quite a gang.
Our lovely calico is female & 14 years old. She’s indoor/outdoor and I think she’d tear the house apart if she couldn’t go outside. It must be that she’s so smart that she survives the outdoors. Her mom was an outdoor cat, so she learned from her too. A friend just got a make calico- three colors.
Fascinating. This article has been printed and is now on my coffee table for education. lol.
So my girls will be spade but the question is (maybe a dumb one?) can/how to up your odds for breeding for calico coloring. Is it even an option?