Girls Only Club! Scientific Reason Behind Feline Genetics and Coat Colouring

As an owner of cats, I've always been interested in their coat colours.

Did you know that most calico cats are female? It's really rare to find a male Calico.

Calico cats have a mixture of brown, orange and white. Credit: Spruce Pets

Calico cats are not a specific breed, more are just known by their coat colour being brown, orange, and white. No two calico cats are the same, so no matter what, each one is unique.

The reason why being a calico is girls only is all due to their genetic code, and how coat colours work in cats.

Just like all mammals, cats have the same genetic coding for sex. XX for females, XY for males.

Not only does this code for sex, but this also codes for coat colour too.

The ability to have an orange coat, or a black coat, relies solely on the X chromosome.

Cats can either have the "is orange" or "is not orange" gene on the X chromosome (explaining why a lot of male cats are orange and it's rare to find an orange female cat).

Likewise with the coding to be a black cat. This is also solely reliant on the X chromosome in the same manner. Cats can either have the "is a black cat" or "is not a black cat" on the X chromosome.

Their genetic code can "switch on" and "switch off", giving the colourful patterns of calicos.

Do you own a calico cat? Did you know this interesting fact? Let us know!