Have you ever wondered why ginger cats are almost always boys, and why this is only a cat issue and not more widespread in the mammalian world?

The specific gene which causes the colouration has long evaded scientists, but two teams of geneticists have recently found the strand of DNA responsible for the phenomenon.

Two separate teams, one based in Japan and the other in America, have finally discovered the Arhgap36 gene’s link to pigmentation.

It has been known for more than a century that a cat’s X chromosome causes ginger fur – male cats have one copy and females have two.

If a male inherits this gene from either his mother or father then he will be ginger, but if a female gets passed the gene from her parents she will most likely not be ginger.

This is because females have two X chromosomes, and one of these mutates (known as gene deletion) during their development as an embryo, and as a result more often than not they go on to become two- or three-coloured cats known respectively as calico or tortoiseshell (with ginger being one of the colours).

It is very rare for a female cat to vary from these genetic colour rules; and because males have only one X chromosome they will be either ginger or not ginger, but never tortoiseshell.

The genetic cause of ginger colouration in humans has been understood for decades – the gene Mc1r governs the distribution of orange pigmentation and the presence of melanin.

However, this gene does not control colouration in cats and finding the one that does has been a genetic mystery for decades.

Both the Japanese and American studies demonstrate that the Arhgap36 gene in a cat’s X chromosome forces the pigment making cells to produce more melanin, which results in a light red colouration.

No-one previously knew that Arhgap36 could affect hair colouration, although its links to hair follicle development were understood, and the discovery of a new molecular pathway for the gene is a cause of great excitement in the world of genetics.

The only things that excite one of our resident ginger cats, Rossi, are food and a comfy bed.

Eight-year-old Rossi is a quirky character, and his unpredictability is the reason he came to us. This gorgeous big boy likes to live life on his terms, and he gets overwhelmed if he’s suddenly stroked or is picked up in a hurry.

During his routine health check the vet established that Rossi has a heart murmur but he does not require any medication for it – he just needs to live a stress-free life in a calm environment, with humans who understand his requirements. In return, he is very chatty and can hold a cat conversation with anyone who cares to engage with him.

Rossi’s personality suits his coat colour, in that it’s one of the rarer colours in the feline world and its really rather beautiful.

Ginger cats may not be commonplace, but they have been around for millennia and evidence of ginger cats can be seen in Egyptian tomb art and in some mummified cats. So, Rossi has a special heritage too.

And to top it all, ginger cats are sometimes called ‘genetic unicorns’ because their orange colouration is linked to sex and this is a rare, if not unique, phenomenon in the mammalian world.

Other species such as humans, dogs, horses, etc can all have orange-like colour variants, but these variants are found in both males and females.