Are Calico Cats Always Female?

Calico cat
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Question: Are Calico Cats Always Female?

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

Answer: First question, 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, a "tortoise shell" or "tortie" cat has a mix of these three colors (blended/swirled together more than distinct blocks of color).

Calico Cats, Gender, and Genetics

Calico cats are usually female.  Why is this? The answer is in genetics. Coat color in cats is a sex-linked trait, a physical characteristic (coat color) related to gender.

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

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 "on" or "off" gives the blotchy orange and black color display.

In Other Words

Since females have two X chromosomes, they are able to "display" two different colors (orange or black, depending what X was deactivated) and white; creating the 3-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).

Coat color is a complex process of dominant and non-dominate genes interacting on the X chromosomes, but that is the basis for coat color in calico cats.

For those of you interested in the detailed coat color genetics, please see the "Related Reading" articles at the bottom of this FAQ.

Can a calico cat ever be male?

Calico cats are not always female. 

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

Interesting calico cat fact: on October 1, 2001, the calico cat became the official cat of the state of Maryland in the United States.