Olivia has a gorgeous fluffy white tummy that I love to tickle when she displays it during one of her yoga stretches. She prefers, however, that I keep my hands off her delicate tummy, so mostly try to I comply. While admiring her tummy one day this last week I recalled an article I read once describing how cat color is formed in the womb. I thought you might be interested too, so I went in search of the article and didn’t find it. As I recall, one fact I thought fascinating was that kittens start out white. The color is produced from top to bottom which is why so many cats have white tummies. Many calicos do, as well as tabbies, 
tuxedo cats and some others. You’ll also notice that a lot of cats have white paws—giving the impression that the gestation period sometimes ends before all of the kitten’s color is dispersed, so the extremities are left white.
I didn’t find that particular article, but here’s one about cat color that is equally interesting. It’s packed with color- and 
pattern-related information—some of which you’ve probably never heard before. For example,
- Cats come in only 3 colors—black, red, or white or some combination or dilution of these colors (black becomes blue and red becomes cream). I read this and I was left wondering about cats in brown shades—pointed Himalayan’s or Siamese, for example, or the Havanna Brown. Turns out that
shades of brown in a cat’s fur actually comes from the black gene. - A white cat is called piebald. I remember when I was involved in horses—a horse with a mostly white face was called a piebald. Interesting term. A white cat is thought to lack pigmentation—so technically white isn’t a color, but a lack
of color. - All cats are tabbies. I can certainly see some striping patterns in Olivia’s calico patches, but what about solid-colored cats? Experts say that many kittens show the tabby pattern when little and that if you look at your cat’s fur in the bright sunlight, you might see hints of tabby, even if the stripes aren’t
Here’s a site that further details some of the points I’ve made here and offers quite an extended lesson in cat color. Enjoy. https://www.catster.com/cats-101/different-cat-colors
