I have heard that all orange tabby cats are male, and to find one that is female is rare and worth up to $1,000. I also have heard that calico cats and tortoiseshell cats are female and to find a male is just as rare and prized. Is there any truth to this?
Your first statement is incorrect. Most, but certainly not all, orange tabby cats are male.
Orange tabby cats are about 80/20 male to female. We have many female orange tabby cats in my practice. There is no monetary value, per se, associated with a female orange tabby cat. Calico and tortoiseshell cats, however, are almost always female.
Here’s how it works. To have black and orange in the same cat, the cat needs two X chromosomes. Two X chromosomes mean the cat will be female. Male cats need a Y chromosome and are XY. Occasionally amutation will arise during embryonic development and a kitten will be born with an extra chromosome: XXY. The two Xs allow for the cat to be black and orange. The Y makes it a male. This is how you get a tortoiseshell or a calico male cat.
Tortoiseshell and calico male cats are uncommon (one out of 3,000 are male), but don’t get your hopes up about breeding these rare cats for money. As a result of this mutation, most tortoiseshell and calico male cats are sterile.