So, why ARE calico cats [almost always] female?

For anyone interested in this tidbit of info:

WHY calico (and tortoise shell) cats are female is that the red/orange (or tan) gene and the black (or gray) gene occupy the same spot on an X chromosome -- so you need two X's to have both colors. A male (normally having one X, one Y chromosome) has to have XXY to have both colors. This is called 'triploid' and I believe such animals are sterile.

The muting gene (making red and black express themselves as tan and gray) and the "white spots" (i.e. calico instead of tortoise) gene are separate and occur in any/all combinations (I don't know what chromosome, but not sex-linked that I know of). Those aren't probably the official scientific names for those genes, but how I remember them. A gray cat has one (or two) black gene(s) and the muting gene, a black-and-white cat has one (or two) black gene(s) and the white-spotting gene (even if MOSTLY white!), etc.

I was fascinated to learn the above, from our "Your First Kitten" book (I think that's where, anyway). Fun stuff.

~'spin!~