On NPR just last week there was a report that talked about DNA in cats and how in calico cats their coloring patterns are a result of chromosomes literally turning on and off or "changing their minds" in different parts of the pigmentation process. It wasn't entirely clear to me how this happens, so I can't make it any more lucid for you.

We were adopted in 2001 by a tiny calico who turned up on our apartment windowsill. She looked like a kitten, and our Siamese mix spotted her and got excited and meowed to call our attention to her. We ended up adopting what was in fact a full-grown but practically starved cat. She has doubled her weight since then (after the operation that happens anyway). These two are perfectly suited to each other, in play and habits around the house. She's quite charming, and there is a little bit of Siamese in this one also. You can see it in the face and eyes, and hear it in the voice. They both like to hang out on the side of the tub, and occasionally both will end up carelessly drooping their tails in your bathwater. They love to visit when I'm working, and my keyboard is so full of hair that I could probably knit another cat from the fur down under the keys.

The cat was so small when she arrived, I suggested several names to the kids that denoted her size. My son finally decided she should be "Clementine," after those tiny little oranges we get around Thanksgiving. Of course, now she looks like she swallowed a grapefruit. ;-)

SRS