OMG you have a calico? I love calicos!
Me too. The redheads of the feline world.
She's pretty fiesty, especially when she first adopted us right after Hurricane Rita. She used to be someone's cat as we took her in to get her spayed and, guess what?
And she's a gorgeous cat. That picture really doesn't do her justice but it's the only one that I have on my laptop.
Is it true that only females can be calico? Why is that?
Not technically. A male with XXY chromosomes can be a calico too.
But generally yes, because it requires two X chromosomes. The reasoning is that when the cat is still young (like, a handful of cells young) one X chromosome will code for one color and the other will be repressed. Then if the current coding chromosome is inactivated (X-inactivation) the other chromosome picks up and codes for a different color, but the cells that have already been created will still have the old set of chromosomes in it (with the first X chromosome still coding) so they'll continue to make one color while the new cells make another color. That's why they have to be females (or a mutated male).
Now, what I don't get is why all male cats aren't solid colors, given the above explanation which was given to me by my genetics professor.