Another type of genetic engineering found in many futuristic settings is cloning. A sample of one creature’s DNA is used to make an exact physical duplicate of the creature. A clone is identical to the original creature in every genetic way—blood type, birth defects, fingerprints, and retinal pattern. However, the clone does not have any scars, tattoos, or other identifying marks gained during the course of the original creature’s life. If, for example, the original creature was born with only one kidney, the clone has only one kidney. However, if the original creature has had a kidney removed, any clone made of him will have two kidneys (as the original creature did at birth).
Cloning is a very difficult process. Although the number of successful experiments has increased, creating and bringing a clone to full term is a high-risk endeavor and scientists generally have to make several attempts before an experiment reaches a satisfactory conclusion. Any single attempt to create a clone has roughly a 90% chance of failure. What’s more, clones tend to be prone to a host of developmental problems including accelerated decrepitude, unexplained organ failure, immune system failure, and a generally weak constitution.