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Originally posted by Threads
(Brief biology interlude)

Females have two X chromosomes, but only one of them is active in any given somatic cell. During embryogenesis, at some stage (16 or 32 cell, I think) there is a random turning off of one X chromosome in every cell. This results in a patchiness, where some cells have one X turned off, and some have the other.

In cats, some coat color regulation is X linked. And in some cats one X chromosome codes for black, and the other codes for orange. Obviously, only a female cat will have this situation; a male will have either the black or the orange.

As the X chromosomes are inactivated, some cells have the black, and some the orange. Hence the calico/tortoiseshell coloring. Impossible in a male cat unless there is an odd chromosomal translocation or extra X chromosome present.

Other coat color factors like agouti, or tabby striping, don't depend on the base color. So there are orange tabbies, brown tabbies, and with yours - a sort of calico tabby.

Now I am confused. Though that was interesting. How do you explain the fact that most orange cats are male? Does this mixed female coloration happen most of the time?