There are many ethical questions that must be answered before cloning becomes a reality. Many of these questions are difficult to answer because all of the facts are still unknown because cloning itself is still in its early stages as a science.
True human cloning involves taking a somatic cell from a person and removing its nucleus. Then the nucleus of a fertilized egg cell is removed and placed in the somatic cell. This is impossible in humans right now because the somatic cells are too specialized and there are many genes that have been switched off in them that we do not know how to turn them back on. However this process was done with frogs. The eggs were implanted with the nuclei from the intestinal lining of tadpoles. Most of these frogs died or grew into monsters but the ones that did grow normally were sterile.
Embryo splitting or blastomere separation is what is most commonly referred to as human cloning. When embryos are in the early stages of development they start to divide into cells called blastomeres. Then zona pellucida (a protective covering for the egg) is punctured or removed and the blastomeres are separated from each other. Each blastomere is then covered with an artificial zona pellucida. Then each of the blastomeres starts dividing and becomes an embryo. This was attempted by Hall and Stillman in 1993. They used embryos that contained too much genetic information and got as far as 32-cell divisions in some the embryos. At this stage the embryo can be implanted in the womb. Another technique is nuclear transplantation. In this process unspecialized embryonic cells are used and their nuclei are removed. An embryo in the 32-cell division stage has its blastomeres separated and then the blastomere is fused with an egg cell by using an electric current or another method.
A possibility for human cloning that has been proposed is that of the embryos that were cloned and not impl