Human cloning is the process of transplanting nuclear DNA from an adult individual into an egg where the nucleus has been removed. The egg grows into an embryo to produce an exact copy of the nuclear genome from the donor DNA without ever needing sperm to fertilize the egg. Dr. Ian Wilmut coined this technique somatic cell nuclear transfer after the first successful attempt at cloning a mammal, a sheep named Dolly, using adult somatic cells.

Advocates of human cloning suggest that somatic cell nuclear transfer may be a useful method for solving infertility problems or preventing inherited mitochondrial disease in offspring. For example, if a husband is infertile or a wife has a mitochondrial disease, the wife's somatic nuclei could be transferred into the cytoplasm of a donor egg and implanted into the wife's womb without ever needing sperm. This is the same procedure that...