Reproductive cloning is the production of a genetic duplicate of an existing organism. A human clone would be a genetic copy of an existing person.
Somatic cell nuclear transfer (SCNT) is the most common cloning technique. SCNT involves putting the nucleus of a body cell into an egg from which the nucleus has been removed. This produces a clonal embryo, which is triggered to begin developing with chemicals or electricity. Placing this cloned embryo into the uterus of a female animal and bringing it to term creates a clone, with genes identical to those of the animal from which the original body cell was taken.
More than eighteen cloned mammals have been produced with SCNT, but claims by rogue scientists to have cloned a human child have been false.
New techniques, such as the derivation of induced pluripotent stem cells via cellular reprogramming, suggest other potential methods of reproductive cloning.
Human reproductive cloning is almost universally opposed. Overwhelming majorities reject it in opinion surveys. Many international agreements and countries (though not the United States) formally prohibit it.
Some oppose reproductive cloning because of safety considerations. Animal cloning is seldom successful, and many scientists believe that reproductive cloning can never be made safe. Human reproductive cloning would also threaten the psychological well-being of cloned children, open the door to more powerful genetic manipulation technologies, and raise other social and ethical concerns.