The most famous clone is Dolly the sheep, but it is a little hard to tell how much Dolly looks like her genetic donor. But Dolly isn't the only animal that has been cloned anymore.

The first cloned cat was born on December 22, 2001 at Texas A&M University. The genetic donor is Rainbow, a calico domestic shorthaired cat. Calico cats typically have fur with patches of black and orange over white. Her DNA was injected into an egg cell that had the nucleus and DNA removed. In the lab, the egg cell was helped to develop into an embryo. The cloned embryo was then implanted into another cat named Allie who gave birth to a healthy cloned cat called CC. Unlike Rainbow, the cloned kitten was born with a striped grey coat over white (a tiger-tabby domestic shorthair). One year later, CC still has her stripes and is more playful than Rainbow, the only cat in the world that shares her DNA.

How strange! Even though CC and Rainbow share the same DNA, while the embryo develops the genes responsible for fur colour can be switched on and off at random to create different fur patterns. This is called X-linked inactivation. Genes and the environment both have an effect while the fetus is growing. Just think, in reptiles the sex of the baby turtles depends on the temperature of the nest, not the genes.

So even if you clone your favorite kitty, you may not get the same cat that you knew and loved. The colour and even personality can be different. On the other hand, cloning may be a first step in reproducing certain animal breeds before they go extinct.

What do you think of cloning domestic pets?

To find out more about CC, check out the Texas A&M University Web site (www.tamu.edu) and the Genetic Savings & Clone Web site (www.savingsandclone.com).