First, congratulations for having such a concrete wish. Here are some ideas that might help you if you find the resources to put them into action. From the many lines of research that may exist for growing a tail, I can think of the following two. 1. Changing your genetic code 2. Transplanting a nice tail Now the explanation, starting from the short one. All the information is based on scientific papers or news, and some websites that look well established. I will not discuss here any ethical issue. I will not always use scientific terminology but also informal expressions. 1. Changing your genetic code Ih the genetic code of humans there is the same information a mouse has to grow a tail, with the difference that in humans this code is not activated. I think you have already got the picture: Change the genetic code in order to activate it, to define the characteristics of the tail (you wouldn't want a mouse tail), and to make the tail grow fast to match your age and size. 2. Transplanting a tail Background and main issues to consider Currently, it is possible to do transplants between species (xenotransplantation: interspecies transplantation), including humans. Examples of transplants to humans include skin, bone marrow, neurons, kidneys, and so on, mostly from monkeys and pigs. Two big problems with these transplants so far are organ rejection and the viruses from the donor. The problem of organ (or even blood) rejection could be approached by changing part of the genetic code or the organ characteristics of the donor to make it closer to that of the human. Some examples are monkeys with human blood and mice with nervous system totally human. The problem of viruses from the donor is more complicated. It is well known by researchers that pigs have a virus that is passed to the human body when some organ, skin or neurons are transplanted. This virus (PERV) so far has not caused any damage to human, but there is no guarantee that it will be safe for any human genetic code. I do not want to frighten you, but I need you to know the magnitude of the issue: the worst scenario is that this virus might combine with human genetic information and evolve into a new form of HIV that could cause an outbreak. Moreover, not all animal viruses are known, so there is always a risk of finding something when it is too late. It is easy to understand why this kind of research does not progress as fast as it could, but let's continue. Other issues to solve Besides the above two problems, you will need to consider the bones, muscles and nerves to control the tail. Only human fetuses and very few documented cases (around 30 so far) of human babies show a tail. The "instructions" for the fetus to lose the tail before birth are determined in the womb. I do not find easy to "reverse" these instructions in an adult like you, so you do not have a tail and also do not know how to move one because you are not supposed to have it. On the other hand, as far as I have read, the tail in babies does not have bones, and in some cases it does not have muscles. Most big mammals, from cats to horses, have bones in their long tails, that give them stability and allows the tails to do some useful functions. So you might want to have bones, muscles and nerves in the tail. Potential solutions Some researchers consider that the tailbone in humans is the remain of the tail lost in evolution. If damaged, the tailbone can be removed with minor or no effect for the patient. Therefore it might be possible to remove the tail bone and connect the transplanted tail to the other vertebrae and to the nervous system in this place. In some experiments with birds, researches have found that transplanting neurons from a species to a different one, the second one can "learn" abilities from the donor. So you may opt to have some neurons from the tail donor transplanted in your brain in order to learn how to control the tail you will also receive. Proposal of experiments Animals Get at least two species of animals, one being that of the donor you choose. It will also help to have at least two breeds of the donor species. For the sake of the explanation, let suppose you chose the donor to be a dog. You will need two breeds of dogs, and another species, which can be rabbits, monkeys, pigs or a combination. I will explain the reasons below. Data collection Do X-ray CT or MRI scans to the animals to understand the anatomy of the bones and nerves. Do fMRI, PET or SPECT scans to determine where are the neurons that "control" the tail movement in every species. Experiment options a) Transplant the tails between dog breeds, to confirm that all necessary data to do at least this have been collected. b) Transplant the tail of the donor breed dogs and some neurons to - rabbits. You can verify if the rabbits can learn to move a totally different tail - pigs. Same reason than above, and better understanding of pig's characteristics. - monkeys (without tail). Same reasons than above. Their brain is closer to human's than that of the other species. Bioengineering work "Inject" the genetic code of the donor dog breed into that of the other species to avoid rejection. "Inject" the neurons that control the tail from the donor dog breed into the brains of the other species to "transfer the knowledge." Xenotransplantation to human If all the transplantations suggested above are successful (no rejection or illness in at least 6 months, and good control of the tail), congratulations! Your turn to make your wish true will come. Good luck.