TalkMore on Twins: Identical Twins Have Genetic Differences
Right on the tails of my last post comes ground-breaking news about identical twins: they don’t actually have identical genetics! (Darn close, but not 100% identical.)
A study by University of Alabama, Birmingham researchers challenges the long-held belief that identical twins have identical genetics. They compared the DNA of sets of twins and discovered significant copy number variation (or CNV).
…[S]ubstantial chunks of DNA sequences were missing, doubled or reversed in one of the two twins. Having chunks of DNA sequences shifted around or missing is a common genetic mutation. When first discovered, scientists thought it was inconsequential. Often it is, but researchers are beginning to learn that sometimes CNV can be a major factor in developing a disease.
This new discovery isn’t just interesting for trivia’s sake, but it holds promise for our understanding of health conditions and diseases. “Changes in CNV may tell us if a missing gene, or multiple copies of a gene, are implicated in the onset of disease,” says Carl Bruder , one of the heads of research. “If twin A develops Parkinson’s and twin B does not, the region of their genome where they show differences is a target for further investigation to discover the basic genetic underpinnings of the disease.”
UAB News Release
DNA Direct’s Alabama native son (not a twin)
Update 3/13/08: You read it here first…but the NYTimes gets the interviews with the good quotes 
The Claim: Identical Twins Have Identical DNA.
Tags: cnv, copy number variation, disease, genetics, genome, identical, research, twins
February 16th, 2008 at 6:39 pm
CNVs for disease might be because of the age of the parents. Especially the male germ line precursor to sperm cells which can multiply every 19 days is subject to copy errors. When areas of testis are closely examined some areas of full of mutated spermatagonia.
February 19th, 2008 at 4:49 pm
Hi Les, what are the implications of the parent’s age (specifically father’s age, as you say) for the discovery that identical twins have differing CNVs? They are arising from the same sperm - so science assumed that they had identical genomes and thus, identical CNVs. Yet, this research has show that identical twins have different CNVs. I’m looking forward to how this line of research will unfold!
April 7th, 2008 at 12:46 pm
How many psychologists still believe in Darl Jung’s theory of archetypes that are transmitted through the genes? The hexagrams in the IChing may be the archetypical human stances and many believe that these are in fact the archetypes. Yet how are these archetypes transmitted? If genetically, then the dreams of identical twins should be similar since they reflect not only unconscious material but also the basic cognitive schema.
Now I have a challenge. If any of you are identical twins or know identical twins, please ask them to participate in a doctoral study that I am doing of the dreams of identical twins. All the information can be found on the above web site, including my phone number if they prefer to call. I am asking five dreams each of each twin in the set. Spread the word!!
Thanks for your help. Margery
April 8th, 2008 at 5:01 pm
As an identical twin, I’ve always been fascinated with the genetic aspect that I was born into. My twin sister and I are both left-handed, middle children born to two right-handed parents. I tend to use my left hand only when writing, and eating. My twin is solely left handed for everything. I find that I’m the mirror of my dad. He’s right handed but he throws, and bowls with his left hand. My twin is artistic, and I have the more academic side of the brain. My running joke is when the egg split, she got the entire artistic side of the brain. We have bought each other the same presents without even knowing it yet we can be different in many ways. It’s intriguing and I feel blessed being born a twin. My twin has always been there with me through all events in life. When I was diagnosed with cancer, I had to ask my best friend; my twin, not to accompany me to the treatments because I couldn’t stand seeing the fear in her eyes staring back at me. She loves me and I love her. I also told my twin that there is a good chance that she won’t get cancer just because her twin did. It could have been caused by things that are not genetic nor identical to her life. I only wish everyone could have a twin and I thank God for giving me mine! My day is made when someone says, in error, “Hello Cherie” to me and I realize that even though we’re 52 years old we can still be mistaken for each other!! Cindy
April 9th, 2008 at 12:43 pm
Hi Margery, good luck in your research!
Hi Cindy, thank you for sharing your experiences as a twin. Best of health to you and your sister!
April 11th, 2008 at 12:22 pm
Hello everyone again. I did not realize that the web site for the dream study did not show. It is http://www.twindreams.info. Cindy and others, please consider joining the study. My phone number for twin sets who want to record dreams is 970-946-0992. Cindy, you and Cherie would be perfect. Please help. Thanks. Margery (twin to Malinda)
P.S. My twin died in an accident when we were 39. I wish I could see what she would have looked like and how similar we would have been.
October 29th, 2008 at 6:05 pm
i too am a twin were turning 14 this december but were not identical but we still sort of dream the same i wonder why?
December 6th, 2008 at 6:20 pm
Margery I am sorry for you loss.
I am an a identical twin and even though we are 40 we still look a like so people say. When I was 18 I started having seizures my sister who slept in a different room than me would go wake up my dad even before I was to have one. Now she carries the seiszure trait her son had them when he was 3. My kids do not and she does not have then either just her 1 son. I love my twin and I love being a twin I will have a best friend for life and I tell people who have twins that. Its funny where ever we go we get a lot of looks its like nobody has ever seen twins together as adults. We are both right handed as is everyone in our family. This is the strange thing her name is Michelle and mine Melissa when I talk to people on the phone who do not know me or know that I have a twin the name I am called the most is Michelle and it freaks people out when I answer them and they say why didn’t you correct me I go I have a twin her name is Michelle I have been called that name by mistake all mylife so I am used to it, they laugh. and she get called Melissa weird Now my twin has some medical issues none serious but my oldest daughter has all the same problems I mean all the same we joke that she is her daughter not mine.