All your favorite orange cats are male, including Morris the 9Lives Cat, Goose from Captain Marvel, and Crookshanks from Harry Potter. Statistically, this checks out, but it doesn’t mean that female cats cannot be orange.
This only happens under certain conditions and requires some basic understanding of biology. Luckily, we’re here to explain below!
Understanding Basic Cat Genetics
Before we get into the specifics of why some cats have orange fur, let’s review basic information about genetics.
The characteristics you see (phenotype) are determined by the genetic makeup (genotype) of an animal. The genotype is made up of alleles, or variations of a certain gene on the chromosomes passed on by the mother and father.
The specific genes inherited from one’s parents carry either dominant or recessive traits that dictate things like gender, fur texture, and even the number of toes a cat may have. In some instances, genes can even influence how friendly a cat is or other aspects of their behavior.
A cat’s coat color depends on which of two base color genes it inherits from its parents: the black gene or red (orange/yellow) gene.
How Orange Coat Color Relates to Feline Genetics
Coat color in mammals isn’t usually linked to gender, but cats are one of a few exceptions. This is because the gene for coat color in cats is contained on the X chromosome.
If you think back to biology class, you might remember that biological females have two X chromosomes (XX), whereas biological males have an X and Y chromosome (XY). When it comes to coat color, this means that female cats have the chance to inherit two different fur color traits, while male cats only have one.
This means males will either have the gene for black or orange fur, with other genes influencing traits like pattern or dilution.
Females can either have two black alleles, two orange alleles, or a combination of the two. If they only have the black gene, their coat will be some shade of black, and the same goes for female cats who only have the orange gene.
If a female cat has both the black and orange fur genes, her body will perform a process known as X-chromosome inactivation. The process randomly deactivates one of the contributing fur color genes and causes the traits to merge into what we consider calico or tortoiseshell colorings, where both orange and black are apparent.
Male Cats with Orange Fur
Male cats, who only have one X chromosome, don’t face the same threat of overdosing on x-linked genes, and they don’t have to reckon with the presence of another coat color gene. In theory, this means that the odds of a male cat being orange or black are 50/50.
In actuality, this depends on the genes his mother can pass down. If she has black fur or any variation there’s no chance of an orange fur gene being passed down. His mother must be either orange, calico, or tortoiseshell to pass down the orange trait on the X chromosome.
If a female cat has both genes, about half of her male kittens will be black while the other half will be orange. If she is orange, all her male kittens will be orange.
The Rarity of Orange Female Cats
Roughly 1 in 5 orange cats will be female, but this number can be more or less concentrated depending on the gene pool of an area.
For example, a cat colony with only black female cats will never produce an orange female kitten. A colony with calico females may match the proposed statistic, while a colony with several orange furred mothers may exceed it.
Orange female cats aren’t as rare as other anomalies (like calico male cats), but the chances of coming across one are still pretty slim.
While many famous cats are sporting an orange coat, every cat is special in their own right.
Rare Male Cat Coats
While orange fur in female cats is determined by genetic background and chance, tricolor male cats only show up under very special circumstances. It’s estimated that fewer in 1 of 1,000 male cats are calico, or less than 0.1 percent.
Most male cats with both black and orange fur undergo a mutation as their skin cells develop. In this instance, their orange fur gene spontaneously reverted to a black fur gene and took over when mapping out their body. This can result in a single black spot or a large chunk of fur depending on when it occurs during development.
Because this only occurs on the skin cells it doesn’t affect the genetic material the male cat will pass on; he’ll still reproduce like any other orange male cat.
Chimerism is another explanation for male cats with orange and black fur. This occurs when two fertilized eggs fuse together in the womb, creating one kitten with two separate sets of cells. If the genes would have made one black cat and one orange cat, the chimera would have equal amounts of both fur colors.
The least likely reason for a calico male cat is that they have an extra X chromosome (XXY) and carry both genes. In this instance the male cats would be sterile, and therefore unable to pass on the orange gene.
