Tortoiseshell an calico describe a coloring found in cats and caused by a combination of specific genetic traits. In female cats, where this trait occurs almost exclusively, it is a result of X-inactivation, in which different patches of fur receive coding for different hair color due to the activation of an X chromosome from either the mother or the father. Calico coloring is a mix of phaeomelanin based colors (red) and eumelanin based colors (black, chocolate and cinnamon). Cats of this coloration are believed to bring good luck in the folklore of many cultures; in the United States these are sometimes referred to as money cats.