Identical twins are more similar to one another than a clone
will be to the person cloned.
President Obama lifted the ban on federal funding of embryonic stem cell research last Monday. Many researchers breathed a sigh of relief as they could finally get to work using these cells to find treatments and even cures for many debilitating diseases and injuries.

Of course, these cells aren’t any less controversial than they were eight years ago. Researchers will still need to destroy embryos to get these cells (at least until they perfect iPS cells which would make this part of the debate moot). Anyone who considers an embryo made up of a few hundred cells to be alive will protest that embryo’s destruction.

This is a legitimate argument based on when someone believes life begins. But some protests I heard were from people worried about embryonic stem cells being used to clone humans. What I can’t figure out is why anyone would want to clone someone.

Cloning won’t be like it is in the movies. Scientists won’t take a cell from someone and make an exact copy of a person who is the same age and has the same memory.

Instead, a human will be cloned like any other mammal. First they’ll remove the DNA-containing nucleus from an egg. Then they’ll fuse that egg with a cell from the person they want to clone.

This “fertilized egg” will then have to grow and develop in a surrogate mother, be born, and then have to grow up. The clone won’t have any of the original’s memories.

In essence, a clone would be more like an identical twin who has been reared apart from his or her twin. Even though identical twins reared apart have a lot of similarities, they have a lot of differences, too. One article I saw put the amount of behavior/personality similarity due to genes at something around 50%.

And a clone will probably be more different than that. When the cell’s nucleus is put into the egg, scientists erase a lot of the markings on the DNA that originally turned it into an adult cell. This “fertilized egg” is now a blank cell which can be shaped by both its genes AND its environment.

Identical twins develop in the same womb at the same time and so are exposed to the same sorts of environmental effects. A clone would not be. And these environmental factors can affect how we develop. They can even alter DNA and as a result, alter who we become.

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Why Human Cloning Shouldn't be a Big Worry 16 March,2009Dr. Barry Starr

  • KakashiHatake

    I think that they should clone people, because if you are an only child, you need atleast a sibling, no matter how young he or she is.

  • The tricky part would be in getting the cloning to work right in people. Now scientists pretty much use trial and error to get it right in animals and they would need to use the same approach for people. That trial and error leads to a lot of miscarriages, birth defects, etc. While this is awful in animal research, it is pretty unthinkable for human research.

  • Jan

    As a married person who was born with a birth defect, and someone who would like to have a child, I would like to clone my husband. He has a 300iq and is working on significant problems that would positively effect society. I don’t want to get some unknown dna in the mix, and I know that his child/twin may not have the attributes that he has, but it’s worth a try. I just don’t want to pass on several heridatary diseases. This I think is a positive social reason to allow human cloning. I don’t want someone else to make my reproductive decisions, just as I don’t want anyone to tell me whether or not I can have an abortion. It’s none of your business. Being in America with the ban, I would have to go to some 3rd world country with who knows what practices to get this done, that may make the medical proceedure more dangerous for the child, as there is no danger to the person who donates cells. As for God not knowing where to put a soul into a created body, I think that you give GOD too little credit, if we can figure it out you know that GOD already has the correct answer and method or we wouldn’t be able to figure it out! As for vanity babies, look at the baby boom in hollywood, it already happens, as do unwanted pregnancies. I would like to have good people copied, if the origional wants to do it. This has to be personal responsibility, I don’t want you to tell me I can’t do it, nor would I as that you take care of the result. My body, my baby, my business. I think that it is an abridgement on my pursuit of happiness that there is this ban, and it should be lifted.

  • Barry

    For right now, the technical hurdles are pretty large. Right now we can only figure how to clone a human (or any other animal for the first time) through trial and error. While working out the conditions, lots of fetuses will be miscarried, babies born dead and babies born with defects. This seems like an awful lot of human loss. In the future as we perfect cloning this may change but for now the human cost is too high.

    Another concern is that we just don’t know the effect of cloning on the clone. Dolly seemed to die young and suffer from diseases that her ‘mother’ did not. Until this is worked out it probably isn’t a good idea to clone.

    BTW I’ve struggled with this a bit too in a more recent blog at There I talk about the fact that we will never have another Einstein and maybe we should clone him.

  • John Morley

    The everyday hypothetical aspects of the human cloning issue are interestingly covered in a TV movie I saw recently; it was sort of a ‘what if’ scenario that dramatized the decision of a young single mother to clone her daughter. Some of it was a bit hokey, but other parts were pretty apt.

    Not sure if it’s still playing, but here’s the website:

  • The movie is still available through Amazon Video On Demand for $1.99. I am going to try to carve out a bit of time to watch it…


Dr. Barry Starr

Dr. Barry Starr (@geneticsboy) is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA and runs their Stanford at The Tech program. The program is part of an ongoing collaboration between the Stanford Department of Genetics and The Tech Museum of Innovation. Together these two partners created the Genetics: Technology with a Twist exhibition.

You can also see additional posts by Barry at KQED Science, and read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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