|Fluff and her unique face|
Most know cats come in a variety of colors, calico being a tri-colored cat (Fluff happens to be a calico). A little known fact is calico coloring is almost exclusively reserved for female cats. Wait, how is this unusual coloration created, and why do only females get it? Both questions can be answered by a scientific principle, X inactivation. Lets break this down to basics, a male has an X and a Y chromosome, where as females have two X's. The X chromosome is far larger than a Y and contains far more information, including the coding for hair color. During the developmental process one X chromosome is dominant over the other therefore the other X is inactivated, but not for long. The two X's take turns. Now if the X chromosomes code for different colors, they will display the calico pattern as the X's take turns switching on and off. Depending on the frequency and duration that each X is on/off you get different size patches or even patches that appear interwoven. This either gives you a brindle colored coat (like Fluff) or a patchwork coat more like a quilt.