In the movies when the crazy evil scientist wants to make a clone he creates a giant incubation chamber full of oozing slime, and from this a body begins to emerge. This looks super cool and is good for the movies, but in the real world creating a clone is nothing like this!

Normally when two people have a baby half of the chromosomes (DNA) come from the mother and the other half come from the father. This is established at meiosis when the egg and sperm are produced, each with half of the total chromosome number. Then, when the sperm enters the egg, its chromosomes match up with the chromosomes already in the egg, creating a cell with the full number of chromosomes which then divides and grows to form a baby. Half of the chromosomes in the baby came from the father, and the other half from the mother. Throughout history, in order to have a baby, there had to be a father and a mother.

However, scientists have now figured out a way around this. First, they take an egg from a woman who is willing to donate one of hers. Then they suck out the chromosomes (DNA) from inside the egg. Now that they have an egg with no DNA in it, they can put in the DNA from anybody they want! To do this, they take a normal cell (not an egg or sperm) from the "parent" and remove its DNA. (Remember that a normal cell already has all 26 chromosomes). They then inject this DNA into the egg, forming an egg cell with all 26 chromosomes-- just as if it had been fertilized by a sperm! However, this new "fertilized" egg is very different, because all of the DNA came from just one person instead of two! The scientists can zap the egg with electricity or give it special chemicals to make it start to divide, and then they have to put it back inside a woman's womb so that it can grow into a baby in the normal way. (If you think about it, men still need women to have babies-- but women don't really need men!)

When the baby is born, it will have the exact same DNA as the person who donated the cell, and therefore the baby is called a "clone". If the scientists ever made a clone of you, it would be a lot like having an identical twin-- only your twin would have just been born as a baby!

Many scientists are very excited about cloning. Not only does cloning help us to better understand the process of human development, but it may also have a lot of useful medical applications. For example, many people hope that one day cloning will make it possible to grow new body parts that are exactly like the original one was, or to develop treatments that would reverse the problems of aging or help cure genetic diseases. However, many people are against cloning, because they think we shouldn't tamper so much with life.

There are many things that we still don't understand. Many of the animals that have been cloned have developed problems later in life that show the cloning isn't perfect, and so it may be very scary to make a human baby clone who will suffer because of the problems. Also people are scared that clones will be treated like slaves or animals or medical experiments, when really they are people also.

What do you think about cloning? Do you think it's exciting, scary, or both?

A clone is an individual who has exactly the same genes as another individual. You might think cloning is new, but you can make a clone yourself! Just find someone you know who really likes plants; maybe a relative, your teacher, or a friend. They can show you how to grow a new plant from a piece cut off of one of their plants. It will be a clone of the first plant.

Animal clones are a lot more rare. Dolly the sheep and CC (for carbon copy) the cat are both clones. They were created by making an egg cell with the genes of an adult animal.

Here are a few things you need to know to understand animal cloning. Each cell has a nucleus, which contains the genes (recipes) for making an individual. Almost every cell in an individual's body has the same genes in it. There are 2 exceptions: red blood cells in mammals and reproductive cells (egg or sperm cells). Every reproductive cell an individual makes is different. When an egg and sperm cell get together, they make unique individuals.

In cloning, researchers take an egg cell and remove the nucleus. Then they take the nucleus from an adult animal and put it in the egg. Now there's an egg cell with the exact same genes as the adult who donated the nucleus. They get the egg to start dividing, then put it in a female animal that is ready to carry the pregnancy. If all goes well, you get a kitten or lamb (or whatever) that has exactly the same genes as the animal that donated the nucleus.

The surprising thing is that the clone may not be too much like the original, they don't look much alike. That's because the environment, even inside the mother, also makes individuals what they are.

But you asked about humans. The process would theoretically be the same, but a lot of people question whether it's a good idea. It took over 87 tries to get a healthy cat clone. Some organizations are also against cloning pets because there are already millions of pets who need homes. On the other hand, some people think that cloning farm animals will make it easier and cheaper to raise them.

There's no proof that anyone has ever cloned a human yet. A group recently claimed that they had. However, they have not provided any evidence.

There are humans who are genetically identical to each other. Who are they?