The genes that control the coat coloration in cats, specifically in the complex calico or tortoiseshell coloring, occur in only one location on the X chromosome within their DNA, and there must be 2 variants of this gene active in order to produce this coloring. Male cats, like any male of a species, have only one X chromosome, so the possibility of a single organism expressing the 2 variants of this gene on their X chromosomes is generally rare and considered a mutation.

Calico cats, with their orange, black and white coloration, are almost always female. So are black and orange tortoiseshells. Why? The answer has to do with genetics. Every cat has 38 pairs of chromosomes; half of the pairs are from the mother, the other half is from the father. Within every chromosome there are thousands of different genes. Every female cat receives one X chromosome from her mother and one X chromosome from her father, while a male receives one X chromosome from his mother and one Y chromosome from his father. Within the X chromosome is a gene for coat color. In calicos and tortoiseshells, one X has the black gene; the other X has the orange gene. White coat color is associated with a completely separate gene. At conception, the kitten is a one-celled organism, which divides until there are millions of cells that make up the final kitten. Each time a cell divides, it passes on its genetic material. For the sex chromosomes, there is a battle for power. This is especially true for the X chromosome. If two X chromosomes are present, which determines female sex, one X chromosome will become inactivated at some point in fetal development. When this happens, all the cells descended from the activated X chromosome will have the same characteristics, including coat color. In calicos, if the X-chromosome that is left functioning carries the orange gene, then all the cells descended from it will result in an orange color. The same is true if the functioning X chromosome has the black gene. If both X-chromosomes carry the same color gene, then the calico pattern will not appear. Since X chromosomes inactivate at various times in each individual cat, color patches vary. The story is different for male cats. Males have only one X chromosome, and it is never inactivated. Whatever color gene is present on this X chromosome will determine the color of the cat. Males can be calico or tortoiseshell only if they are born with 2 X-chromosomes and a Y (XXY), allowing one X to be inactivated. This genetic defect (XXY) is very rare. It is difficult to breed specifically for calico or tortoiseshell cats. Breeding an orange cat to a black cat may increase the chances, but it all depends on whether the kitten is female and at what stage during development the X-chromosome becomes inactive. There is no way to predict or force an X chromosome to inactivate at a certain point in development. I know I know this sounds like alot to absorb, but basically it means it is easier for the genes to make girl kitties than boy kitties in this breed. I have had and seen male calicos, however most are usually sterile. If you have a male calico get him checked for fertility. Hope this helps.

Usually, but not always. Chances of a male calico are approximately 1 in 3,000.

I remember reading somewhere that male Calicos can happen but they are always sterile and cannot reproduce.

Calico cats, with their orange, black and white coloration, are almost always female. So are black and orange tortoiseshells. Why? The answer has to do with genetics. Every cat has 38 pairs of chromosomes; half of the pairs are from the mother, the other half is from the father. Within every chromosome there are thousands of different genes. Every female cat receives one X chromosome from her mother and one X chromosome from her father, while a male receives one X chromosome from his mother and one Y chromosome from his father. Within the X chromosome is a gene for coat color. In calicos and tortoiseshells, one X has the black gene; the other X has the orange gene. White coat color is associated with a completely separate gene. At conception, the kitten is a one-celled organism, which divides until there are millions of cells that make up the final kitten. Each time a cell divides, it passes on its genetic material. For the sex chromosomes, there is a battle for power. This is especially true for the X chromosome. If two X chromosomes are present, which determines female sex, one X chromosome will become inactivated at some point in fetal development. When this happens, all the cells descended from the activated X chromosome will have the same characteristics, including coat color. In calicos, if the X-chromosome that is left functioning carries the orange gene, then all the cells descended from it will result in an orange color. The same is true if the functioning X chromosome has the black gene. If both X-chromosomes carry the same color gene, then the calico pattern will not appear. Since X chromosomes inactivate at various times in each individual cat, color patches vary. The story is different for male cats. Males have only one X chromosome, and it is never inactivated. Whatever color gene is present on this X chromosome will determine the color of the cat. Males can be calico or tortoiseshell only if they are born with 2 X-chromosomes and a Y (XXY), allowing one X to be inactivated. This genetic defect (XXY) is very rare. It is difficult to breed specifically for calico or tortoiseshell cats. Breeding an orange cat to a black cat may increase the chances, but it all depends on whether the kitten is female and at what stage during development the X-chromosome becomes inactive. There is no way to predict or force an X chromosome to inactivate at a certain point in development. I know I know this sounds like alot to absorb, but basically it means it is easier for the genes to make girl kitties than boy kitties in this breed. I have had and seen male calicos, however most are usually sterile. If you have a male calico get him checked for fertility. Hope this helps. I have answered this question before here: http://www.answerbag.com/q_view/90302

Off topic but, I wonder what the odds are of a female orange tabby. I have one, and she's incredibly loyal, and loving towards me.

Yes. They are, we called our vet today to ask for a test to be done on our male calico kitten. He is two months old today. His name is Snookie. :) Our vet told us that they are rare. The picture is of Snookie and my Fiancée. The father was a orange tabby that looked like Garfield, and then the mother is a pure black cat. The father was put down two months ago, due to old age and getting real mean.

I am not sure how rare it is, but these three are now 3 weeks old and they are male...also inthe litter of five were two Siamese both female. 2 I believe are considered tortiseshell and one is Tru-Calico...

had a true long haired MALE calico that suddenly died last week. I am devastated. Not that he was "rare" in color but because he was such a dog like cat and a big loveable puss. He loved to be around people and always wanted to snuggle up close to your neck. He was only 6 and threw up after eating one night and was laying on the ottoman with his head low like he didn't feel good while we were watchng TV. In the morning I went to look for him because he is always around and wasn't when I got up. I found him dead with bright red blood around his mouth and in front of him. He loved to eat and was shaped like a football. I looked up causes and think he had kidney or upper GI problems that caused an ulcer to explode. He was just at the vet for shots and check up last month and the vet said he was fine. I now wonder if its true about them being defective. You can see his photo on myspace if you search me janetcraig08 and look at my photos. He was a REAL male Calico. Orange,black,white and brown in patches. crap I miss him( crying:( )

Because male calicos die shortly after death!!!