Cloning

Cloning is a controversial topic in stem cell research, people believe that clones will be a 'carbon copy' of the original, but that’s not true. The reality is, cloning is an alternative way of creating an embryo, not a way of copying a fully developed organism. That embryo, once created, is just that: an embryo. Some people fear that 'mad scientists' will recreate such historical figures as Hitler and Stalin. While it is possible, if the scientist had adequate DNA from either man, for a scientist to create someone with matching DNA, the clone would not be the same 'person'--their consciousness would be entirely different than anyone they could have been cloned from.
Also consider the case of Rainbow and CC. CC, which stands for Carbon Copy, was the very first cloned cat. Although CC is an exact genetic copy of Rainbow, each cat has very distinct colorations on their coats. The reason for this is in the X chromosome, which contains a gene that helps determine fur colorations. Because they have the same X chromosomes, each cat has the same two coat color genes--one for black and one for orange. But early in Rainbow's life, each of her cells "turned off" either an entire black or orange color gene. This is called "X-inactivation", and is a very common occurrence in female cats. X-inactivation is how calico cats such as Rainbow develop their complex markings. The specific somatic cell that was used to create CC contained an active black color gene and an inactive orange color gene. As CC developed, her cells stayed exactly the same as that initial one. The result is CC's notable lack of any orange markings.

http://www.mun.ca/biology/scarr/Cloned_Cat.html