Calico cats are not a specific breed of cat. Calico refers to the color pattern of the cat's fur. Calicoes have three distinct colors that appear in large blocks. The three colors, black, white and orange, must be present for a cat to be a calico. Gray, cream and ginger are variations of these three colors. (Photo: Saint Lazar/Flickr)

In cats, the genetic code for orange and black are on the X chromosome. Because females have two X chromosomes (XX), while males have and X and Y (XY), females can exhibit both orange and black, while males can only exhibit orange or black. The gene for white is unrelated to the sex-linked colors of black and orange.

Occasionally, male cats are calico due to an abnormal condition that causes them to have two X and one Y chromosome. (XXy). Photo: shecodes/Flickr) In in my part of Maine, we refer to calicoes with predominate white coloring as money cats and the darker colored calicoes as "calico", but they are both a type of calico cat. Most calico cats are female, because coat color is a sex-linked trait. (Photo: leasqueaky/Flickr)