Calico is not a breed of cat, but an unusual coloring occurring across many breeds.
This coloring is caused by a combination of specific genetic traits. Calico coloring is a mix of phaeomelanin based colors (red) and eumelanin based color (black, chocolate and cinnamon). Cats of this coloration are believed to bring good luck in the folklore of many cultures.
Virtually all calico cats are female; a male calico is a genetic anomaly and usually sterile. Producing calico kittens through selective breeding also is nearly impossible due to unpredictable actions of genes and chromosomes when cells multiply in a feline fetus.
A calico cat must be a tri-color, with its three colors in distinct patches, not mixed as in a tortoiseshell cat. To be a true tri-color, a calico cat's colors must be:
- ~~> white
- ~~> red or cream; and
- ~~> black, blue, chocolate, lilac, cinnamon, or fawn.
The variations in color from red and black are caused by a gene which dilutes, or lightens up the basic color, and produces a dilute calico cat, most commonly with a coat of white, cream, and blue.