this is from CatFancy magazine (Jan2002) article by L.Shelton-

"the calico cat takes its name from a colorful cotton cloth imported from Calicut, India.

"the only breeds that can't have calico kittens are Abyssian, Burmese, Bombay, Chartreux, Egyptian Mau, Havana Brown, Korat, Ocicat, Russian Blue, Tonkinese, Siamese, Singapura, Somali...all other breeds have the genetic combinations necessary to make calicos.

"logic leads us to the conclusion that male calico and tortiseshells cannot exist, because males have only one x chromosome and, therefore, only one of the two basic colors needed...(but)

' A recent study of a group of 10,000 cats coming into veterinary clinics...found the incidence of calico/tortiseshell males to be 4 cats per 1000.

"11 of these male calicos were studied further...some were XXY (sterile) but over half were determined to have both XX and XY cells , and to be fertile.