Contrary to popular belief, a calico cat is not a specific breed of cat. It is instead an unusual pattern of coloring that can occur in many different breeds, including Manx, Persian, and Domestic Short-Hair cats. To be considered a calico cat, a cat must be tri-colored, with patches of white, red or orange, and black fur. Some breeds have rules as to what percentage of the cat's fur must be white for it to be called a calico cat. Calico cats are nearly always female. This is due to the genes for the orange or black color being on the X chromosome. Female cats have two X chromosomes, while male cats have an X and a Y chromosome. Therefore, the mother cat passes the X chromosome on to her kittens, while the father passes either the X or Y chromosome, thus determining the kittens’ sex. To be a calico cat, the kitten must have an X chromosome that has the orange color and an X chromosome that has the black color. Male calico cats are genetic anomalies, with XXY chromosomes and are sterile and extremely rare.