 Strictly speaking, cloning is the creation of a genetic copy of a sequence of DNA or of the entire genome of an organism. In the latter sense, cloning occurs naturally in the birth of identical twins and other multiples. But cloning can also be done artificially in the laboratory via embryo twinning or splitting: an early embryo is split in vitro so that both parts, when transferred to a uterus, can develop into individual organisms genetically identical to each other. In the cloning debate, however, the term ‘cloning’ typically refers to a technique called somatic cell nuclear transfer (SCNT). SCNT involves transferring the nucleus of a somatic cell into an oocyte from which the nucleus and thus most of the DNA has been removed. (The mitochondrial DNA in the cytoplasm is still present). The manipulated oocyte is then treated with an electric current in order to stimulate cell division, resulting in the formation of an embryo. The embryo is (virtually) genetically identical to, and thus a clone of the somatic cell donor.