Why Are So Many Calico Cats Female

A sleeping calico cat
A Sleeping Calico Cat

Many people are surprised to hear that the vast majority of calico cats are female. Why is this? Can a calico cat ever be male? Learn more about the genetics of coat color in felines.

What Is a Calico Cat?

A calico cat is not a breed of cat, it is a color pattern. To be called calico, three colors must be present: black, white, and orange. Variations of these colors include gray, cream, and ginger. A true calico cat has large blocks of these three colors. Other names for calico cats include tortoiseshell or torties, brindle, or tricolor cats.

Beautiful Calico Persian Cat
Beautiful Calico Persian Cat

Gender and Genetics

Calico cats are usually female, this largely due to genetics. Coat color is a complex process that is the result of dominant and non-dominate genes interacting within the X chromosomes. Since coat color is a sex-linked trait, it is one of the cat's physical traits that vary based on gender.

Female animals have two X chromosomes (XX), while males have one X chromosome and one Y chromosome (XY). The genetic coding for having black or orange color in the coat is found in the X chromosome. The color display is either orange or black. The coding for white is a completely separate gene.

orange tabby cat
orange tabby cat

In female mammals, one of the X chromosomes is randomly deactivated, called X-inactivation, in each cell. For calico cats, the random mix of color genes that are activated or deactivated gives the blotchy orange and black color display.

Since females have two X chromosomes, they are able to have two different colors (orange or black, depending on which X was deactivated) and white; creating the three-color calico mix.

Since males have only one X chromosome, they only have one black or orange gene and can only display orange or black (plus or minus white, controlled by another gene).

short-fur gray cat
short-fur gray cat
brown tabby cat on white textile
brown tabby cat on white textile

Male Calico Cats

Calico cats are not always female. Male calico cats do exist and typically have a chromosomal aberration of two X chromosomes and one Y chromosome (XXY). Cats with this chromosomal configuration are usually sterile, which means that they are not able to breed. This syndrome is similar to a condition in humans called Klinefelter's syndrome, or XXY syndrome.

Midsection Of Boy With Cat
Midsection Of Boy With Cat

Cool Calico Cat Facts

On October 1, 2001, the calico cat became the official cat of the state of Maryland in the United States. According to the folklore of many cultures, Calico cats are believed to bring good luck. Japanese sailors often had a calico ship's cat to protect against misfortune at sea.

Other Coat Types

Cat genetics is responsible for producing many different varieties of cats and coat types. Common types include the bicolor or tuxedo cat (mostly black with a white chest), striped or marbled tabby cats, and solid color cats.

White cats—true albino cats—are quite rare. Much more common is the appearance of white coat color that is caused by a lack of melanocytes, or pigmentation cells, in the skin. White cats with one or two blue eyes have a particularly high likelihood of being deaf.