Recent advances suggest that it will soon be possible to clone humans. Early uses are likely to include enabling reproduction by infertile and gay couples.

Clones are not unfamiliar, as they are already among us in the form of twins. Twins are in fact more similar than a clone of an adult will be to that adult, because the twins grew up together or at least in the same time period. A cloned baby will grow up in a different environment, and will begin to diverge from its “parent” as soon as it is implanted in the womb.

The reasons for this are simple:

• People are only partly genetically determined.
• Expression of a person’s genetic code is influenced by the environment.

Cloning cannot result in an instant adult, or a person with the “parent’s” memories. These would require two technologies that are many decades away at the earliest:

• The ability to accelerate growth in an embryo. That would result in an infantile adult, as it would never have a chance to learn. That problem could perhaps be dealt with by the second technology.
• The ability to record, store, and download the mind. Physics may prohibit it, but if it were possible the parent’s mind could be downloaded into the adult clone, probably in some kind of implant, as the brain is physically shaped by its environment and would not be set up to hold a lifetime of experience.

A likely use of cloning within decades is parts replacement. People may grow replacement organs and other parts as needed, or keep a stock of them in case need arises. To avoid ethical issues, they would not be grown as part of a complete body.