So, as most of you know, cloning is possible, and is being practiced in our modern era. Cloning, usually, creates an baby with the exact same genetic code as the person they got the DNA from. The clone has to be a baby, and grow over many, many years to adulthood, just like the person the DNA was taken from.

In my story, it’s necessary for the clone to be an adult soon after being cloned. My question is, how can you clone a fully grown adult to be an adult?

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    $\begingroup$ Really the question is how can I make a baby grow up super fast. If you could do that, you would have an adult that was not potty trained and did not know how to talk. Not that there is anything wrong with that, but if you are such an adult let's put some towels down before you ride in my car. $\endgroup$
    – Willk
    Aug 20, 2018 at 0:23
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    $\begingroup$ You need to be more specific about what this instant-adult needs to be able to DO. This is a pretty common conceit in science fiction, I can think of at least half a dozen science fiction novels/movies/tvshows off the top of my head that do it. in MOST cases though, the instant-adult clone is just a vessel into which the personality and memories of the original are poured somehow. If that's the scenario you're thinking about, then you have one answer. If the instant-adult clones have to be completely independent of their source, that's a completely different answer. $\endgroup$ Aug 20, 2018 at 0:54
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    $\begingroup$ @Wilk Depends on what the clone is for. Spare parts don't need education and if you have mind transfer tech, it doesn't matter. If you have forced learning or imprinting, it also doesn't matter. $\endgroup$
    – Thorne
    Aug 20, 2018 at 1:12
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    $\begingroup$ What needs to be identical? In general, memories are considered to be harder to clone than physical appearance. $\endgroup$
    – Cort Ammon
    Aug 20, 2018 at 3:16
  • $\begingroup$ Pretty sure this is a Duplicate cloning question or at least highly related $\endgroup$ Aug 20, 2018 at 11:22

5 Answers 5


Rather than cloning I would use 3d printing that can produce a perfect copy of a human.

Either that, or basically give him a form of limited cancer, where all cells divide at an abnormal rate, and once the cells have divided the same amount of times as the average adults you cure the cancer. This probably means programming a cancer that will divide a fixed amount of times with one 'good' set of dna surviving while all others have a fixed amount of divisions before they destroy themselves. What would be left over is the normal human cells.

Or, you could do what the immortal jellyfish does and take adult dna and revert it to a stem cell, then inject it into a brine with the necessary nutrients for it to redevelop back into an adult, though their brains and muscles will both need development outside the tank which may defeat the purpose.


As a pure mathematical problem, the absolute minimum is just over 46 days.

A human cell takes on average 24 hours to divide. To reach the estimated 37 trillion cells that makes a human body, cells need to double every day for 46 days

That's assuming every cell divides every day.

The clones in Star Wars took several years to grow to adult.


Utilizing the Unsettling Implications Of Teleportation to your Benefit

I don't know how advanced your society is, but they clearly have fully functional cloning that not only perfectly duplicates another person, but allows them to be fully grown and presumably fully psychologically functioning within a matter of days. Remember, life experience is kinda important otherwise you just have a screaming pooping and flailing infant in an adults body, so you are going to have to hand-wave some kind of memory transfer into the mix if you go the cloning route.

So we're already hand-waving a ton of stuff, so why not clean it up a bit. If you are using some kind of star-trek matter transporter there is a few things you can do with them other than travel. So obviously, through pure contrivium based quantum physics you have figured out how to break a person down at the atomic level, record that info, then transmit it before putting them back together at the desired destination. So why not just keep a saved copy of that information from whomever you desire to replicate and just re-assemble as many copies as needed as often as you need them? Its not just a person with the same genetic code, its exactly the same person who went into the trans-mat machine to begin with perfectly duplicated at the atomic level.

Its not exactly the hardest of science answers, but neither is popping a days old adult body from a gestation tank and expecting it to actually be a functional adult and not some fully grown but psychologically disabled infant without using the equally science-fantasy concept of consciousness transferal.

  • $\begingroup$ It’s nog supposed to be psychologically grown. It’s supposed to be a newborn in an adults body. That’s how it’s supposed to be in my story, otherwise the story doesn’t work. Good answer though. $\endgroup$
    – DT Cooper
    Aug 20, 2018 at 22:23

Approximately the same time as it has taken the original to arrive at the same age and physical condition, obviously!

Yet this may not quite be acceptable from a plot point of view, so here's a few pointers on reducing that time frame, contingent on the use of the clone.

Spare parts

You don't actually need a full clone for this, it should be possible to graft the organ to be replaced onto a bio-compatible host and with growth/rate accelerators you'd be looking at several months to years. Some organs are problematic: the brain, for instance (we simply don't know enough about the interconnections between all the neurons except that these interconnections are partly created through learning by the individual), but also muscles as muscles need a work out to be compatible with the individual receiving the spare part. On the bright side, you can require some re-validation therapy and it may be advantageous to use a younger version of an organ.


The practice where a much younger clone is used as a replacement body when old age becomes a hindrance. This requires a mind transfer technology which presumably fixes the neuron and neuron interconnection problem. There is plenty of time to grow a body (say, twenty years) and the clone body does not need much exercise and can be kept unconscious during the entire growth cycle. A period of up to a year of exercising the new body after the mind transfer (the old mind has to adapt to the much younger body) is probably acceptable as well.


The practice where a clone body is offered as a replacement in case of accidents or after being murdered. Again, this requires a mind transfer technology in addition to regular mind recordings as a backup to restore onto the blank slate. This is one of the more difficult use cases as it requires the body to be grown fairly fast, say less than five years, while keeping it a blank slate. Another problem is to copy the physiological impact of the environment on the new body, i.e. scars, wear and tear, and so on. Without this the clone will not have an identical or even similar look! Again an adjustment period of the recorded mind to the new body of a year is acceptable.


This is the use case where the genotype of successful individuals are copied to augment (or supplant, whatever the plot is) the general population. The problem here is to copy the environment and learning processes too as the phenotype is the determinant of success, not the genotype on its own. However, decades to grow and learn a clone into an individual are permissible, as each copy will be an individual, albeit very similar to another copy.

Other uses

There are probably other very creative uses of clones but the main things to consider are:

  • in how far does the phenotype (result of environment and genetics) of the clone need to match the original? A blank slate is much easier than a fully trained individual.
  • how much time do you have to prepare the clone in advance? If you need anything less than a couple of years, I'd seriously look into biological 3D printing and infusing the 3d printed cells with the DNA from the host.

The classic way to address this is to just ignore the scientific and moral ramifications and complications of actual cloning. What happens is you get the egg and sperm and put it into a giant test tube that provides it with all the necessary nutrients to grow. If that bothers you, than you can upgrade it to a fetus, which is removed from a surrogate mother or a newborn child who is removed via c-section and placed in the tube. Either way, you get a baby into a giant test tube.

The test tube is designed to accelerate the growth, the actual speed is up to you. You can make it take decades, years, months, days or minutes. In Altered Carbon, the main character is able to create a clone of himself in what feels like a few minutes, this could be some advance 3D printing or a very fast accelerated cloning process. You could also have blank human clones, which you merge with DNA and then they will form the shape of the hosts DNA. Its also show in futurama with a more classical test tube approach. As for actual growth methods, it could be chemical induced, via sonic ways which improve growth or maybe you have a localized time machine.

Once you have a full sized adult you going to need to give it some memories. No one needs a full grown adult who can't talk, walk and shits themselves at will. You can map out the hosts brain waves and transplant them into the clones mind, effectively duplicating the host, maybe you can imprint the memories, by forcing them to watch videos and descriptions of all their exploits and daily life.

The biggest issue with any fast cloning, is your going to need to make it expensive, or rare enough so that no one else thinks of using it, or can use it. It could be restricted technology, extremely expensive, banned and punishable by death.

Another suggestion would be to have a duplicate, sort of the same as the Mission Impossible style, with a full face mask and voice changer. If your even more dedicated, you could apply corrective surgery to ensure their body is the same shape as the host. The duplicate person would simply need to memorize any life or large achievements and history of the host to be able to roughly duplicate their behavior and actions. This would be possible with today technology I believe. While the mask in Mission Impossible are a bit rough, there are professionals who can make you real life masks to be able to perfectly imitate another person.

  • $\begingroup$ 'you get the egg and sperm', that is not cloning, that is in vitro fertilization. Cloning uses a cell from the original body (not a gamete). Usually stem cells are used for this but it can be other cells too because apparently you can revert them to stem cells although this is still an active area of research. $\endgroup$
    – GretchenV
    Aug 20, 2018 at 10:57
  • $\begingroup$ It’s supposed to be an infant in an adults body. That’s how it’s supposed to be in my story, otherwise it doesn’t work? $\endgroup$
    – DT Cooper
    Aug 20, 2018 at 22:26
  • $\begingroup$ @RobertPaul If you want, you can go with that. Memory scanning and implanting is science fiction after all so you can remove that section. $\endgroup$
    – Shadowzee
    Aug 21, 2018 at 1:47

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