A further reason is to obtain a supply of stem cells. Stem cells in embryos are very flexible and can develop into every other type of cell in the body. For example,it could help someone recover from a disease,repair human tissue,or help them walk again after an accident. These stem cells would need to come from an embroy taken from the clone of someone. But the embryo would then be wasted,which many people find unacceptable. What is clear is that some voluntary code of practice among scientists has to be agreed.If not, compulsory government regulations will have to control cloning.
A fourth reason for cloning is that some scientists and farmers think it would be handy to clone,for example, a prize cow which can resist bacteria or disease,or to sow a cloned crop which can resist rot or pests.But to rely on a few cloned animals or crops would restrict the biodiversity of the breed.
Finally ,the latest research into DNA has helped solve crimes by analyzing the suspect’s saliva which they spit at a crime scene or the dirt under their fingernails.

一个深层的原因是去建立干细胞的供应。干细胞正在变成一种非常灵活并能变成身体中各种类型的细胞。例如，它能帮助人们从一种疾病中恢复，修补人类的组织，或者帮助人们从一场车祸后恢复行走。干细胞需要来自克隆某人的一个胚胎，但这个胚胎将被浪费，这是许多人所不能接受的。一些实践自律手则在这些科学家中被赞同，这些是很清楚的。如果不这样，强制政府发规将不得不制定以控制克隆。
克隆的第四个原因是许多科学家和农场主们认为克隆是唾手可得的，比如，一只珍贵的能抵抗细菌和疾病的母牛，或者播种能抵抗腐烂和害虫的庄稼，但是依赖很少动物和庄稼的克隆将限制物种的多样性原则。最后，最新的DNA研究已经帮助通过嫌疑人的在犯罪现场的唾液和指甲缝里的污垢去揭示罪行。