Twins: Not so identical after all.

Nearly identical twins: The difference being, of course, that the boy on the left thinks only evil thoughts.
Nearly identical twins: The difference being, of course, that the boy on the left thinks only evil thoughts.Courtesy Chubby Bat
Genetic studies have recently revealed that identical twins are only mostly identical.

Identical twins, by definition, should have the very same DNA. While the genome is virtually identical, says a report in the American Journal of Human Genetics, there are tiny and fairly common differences in the genetic makeup of twins.

Each set of twins involved in the study had the same DNA, but “evinced differences in the number of copies of individual DNA segments.” So some twins could have multiple copies of a segment of DNA, while their siblings might be missing the same segment altogether.

The study complicates our view of genetics, but might lead to a better understanding of why identical twins sometimes have significant differences in health. Parkinson’s disease, for instance, can develop in one twin and not the other, and until now environmental factors were thought to be the only explanation for that sort of thing.

What’s most remarkable about the study, to me at least, is that these geneticists claim to have discovered something that I learned from watching a video when I was seven. I am, of course, referring to the 1988 documentary Twins. The film follows two separated-at-birth twins, within whom a keen observer can detect subtle discrepancies in morphological phenotypes. One of the brothers, Julius, looks strikingly like a younger version of California’s governor, while the other brother, Vincent, looks a little more like some kind of goblin, possibly a gnome. Also, Vincent has latent criminal tendencies, and Julius is cursed with deeply sub-average intelligence. So while this study sheds a certain amount of light on the subjects of the film, I’m not sure that the scientists should go around talking about “original research.” At the very least, I hope that Ivan Reitman is credited in their bibliography.

Your Comments, Thoughts, Questions, Ideas

mdr's picture
mdr says:

My dad is an identical twin and he always says he and his brother had to be twins because one guy couldn't be that dumb.

Okay, I'm not sure if this adds anything to the posting but I always found wisdom in it.

posted on Sun, 02/17/2008 - 11:19pm
Kira's picture
Kira says:

I think their relly awesome to me, one of my friend is a twin. They don`t look alike but they are twins.

posted on Mon, 02/18/2008 - 11:39am
Anonymous's picture
Anonymous says:

Do identical twins have identical fingerprints? If not, why not?

posted on Tue, 02/19/2008 - 8:27am
JGordon's picture
JGordon says:

According to this, identical twins do not have identical fingerprints. Fingerprints are formed during fetal development, and their characteristics are supposedly influenced by external factors like "maternal diet, pH, temperature, movement of the fetus, etc." as well as by genetics.

How about that?

posted on Wed, 02/20/2008 - 6:48pm
AlexG's picture
AlexG says:

Identical twins don't have finger prints as the precise patterns on your fingers are affected by the local environment (pressures etc..) you experience in the womb. This will be different even if their are two individuals sharing the womb.

posted on Thu, 02/21/2008 - 5:50am
Amy Grace's picture
Amy Grace says:

No, everyones fingerprints are different, even those of identical twins.

posted on Sun, 06/17/2012 - 4:42pm
koallainfestation37's picture
koallainfestation37 says:

dude thats crazy
i got 2 twin sisters
i had no idia

posted on Wed, 02/20/2008 - 10:36am
porscha2008's picture
porscha2008 says:


posted on Wed, 02/20/2008 - 10:37am
JGordon's picture
JGordon says:

Yeah, it must have been a rough life for the good and evil twins--one of them always wanting to help old ladies across the street, the other always wanting to commit mail fraud. That may not have been genetic, though, so I think you're probably safe if you ever do have twins.

posted on Wed, 02/20/2008 - 6:51pm
shanee's picture
shanee says:

This information is right on because hopefully everybody knows that twins arent identicle they look mostly like eachother, you've never really seen twins that actually look just alike. so good job on gettin this info out kiddo!

posted on Wed, 02/20/2008 - 10:39am
LEE's picture
LEE says:

My friend has a twin, but they're not really identical. It's just like the movie Twins as you wrote. One is taller and slimer and the other one is short.

posted on Wed, 02/20/2008 - 10:45am
Candice's picture
Candice says:

I have a twin. But she's really not my twin. I mean we look alike and everything but where not twins i guess. Since I thought all twins have the same dna, i guess where not twins anymore...SAD... No but that's wierd so now they have to rethink everything that they said about twins having the same dna and everything. So now people with serious illnessess can't use their twins organs like the liver or kidney translpant? Wow were all doomed?

posted on Wed, 02/20/2008 - 10:49am
JGordon's picture
JGordon says:

I think you're still twins, Candice. And I think if you ever need your sister's liver or kidneys your should still be covered (although she might be kind of sore about you taking her liver).
What the research was saying, as far as I understood it, is that the information encoded in your and your sister's DNA (for example) is still exactly the same, but there are probably sections of the DNA that one of you has more of than the other--and scientists still aren't sure how having more or less of these sections effects your health.

It'd be like, maybe, if you and your sister had identical jeans, but one of you had an extra belt loop.

Get it? Jeans? Genes? Oh ho ho ho.

posted on Wed, 02/20/2008 - 6:41pm
shanee's picture
shanee says:

Its me again..and umm oh yeah ive heard that people, everybody, has a twin but not an identicle one.

posted on Wed, 02/20/2008 - 10:57am
Anonymous's picture
Anonymous says:

i have twin girl cuzins they are the most cutiest too they are identical they dress alike look like can you harly tell them apart i think its so cool

posted on Wed, 02/20/2008 - 11:09am
Looney_Tooney's picture
Looney_Tooney says:

Forreals!!! One is evil and one is good?!?! That's just crazy yo.

posted on Sun, 02/24/2008 - 1:46pm
Twila's picture
Twila says:

When you think twins you think "alike." I never really thought that identical twins would think the same that's why this isn't so much of a surprise to me. I think it's kind of different in a way.

posted on Wed, 02/27/2008 - 11:00am
Unctwin2's picture
Unctwin2 says:

I am an identical twin (now 40). We have always had many identical features but appear to "mirror" each other. I part my hair on the left, she on the right. She does many things "left handed" . When we walk together, we have to be on a certain side of each other...and it's just a given. We both had two daughters. As we have gotten older, we still "look alike". I am bigger in weight than she is by a few pounds. This comes in because I actually like to cook and eat. She does not. The interesting part is that when we were in college (and yes, roomed together), she did all the cooking.
There are differences in us but yet, we still get stared at in the mall. We still think a lot a like but we also have somewhat different lives. We actually complement the other's weakness. She is still my best friend and I believe, a part of me.

posted on Wed, 03/05/2008 - 11:37am
Anonymous's picture
Anonymous says:

I'm a mirror twin also somewhat similar likes , personallity alot differant. That's probably because we stopped hanging out togerther when we were teens. We are about thirty pounds differant in weight, though. So, I'm always so happy if someone notices that we are twins.

posted on Thu, 02/12/2009 - 4:53pm
Lacey's picture
Lacey says:

Unctwin2, that was really cute.. i think it's sweet when siblings get along. (with my brothers, well, i try, but seriously it's really hard when you're the only girl! haha) I think twins are simply adorable and someday i'd love to have twins of my own if i'm lucky!

posted on Fri, 06/13/2008 - 1:12am
Anonymous's picture
Anonymous says:

I'm a twin and recently started wondering if we are identicle because I heard it could be one egg and two sperms which would not be the same as if there were one egg with one sperm that split. My twin was hurt that I would question this but I'm curious. So maybe this does explain why we are a little differant (one left handed one right,etc.) but so much alike. Twins are awesome!

posted on Thu, 02/12/2009 - 4:48pm
Anonymous's picture
Anonymous says:

I'm also a twin and have also started wondering if we are identical, we seem to grow less and less alike. I have dimples and she doesn't (someone told me that was genetic) but our parents always told us that we were. It jus feels kina weird not knowin if we are identicle or not.

posted on Mon, 08/31/2009 - 1:22pm
Anonymous's picture
Anonymous says:

i think thats a great artical but i have one question that has to be answered its an emergancey !!!!!!!!!

q.1 how do scientists think twis are formed ???

posted on Fri, 10/29/2010 - 3:56am
mdr's picture
mdr says:

Simply put: In the case of identical twins (monozygotic) a single egg splits into two embryos soon after fertilization. With non-identical twins (dizygotic) two separate eggs are fertilized. These are sometimes called fraternal twins. In the former the twins share a single placenta. In the latter each twin has its own placenta.

Read more here

posted on Fri, 10/29/2010 - 1:07pm
Anonymous's picture
Anonymous says:

I'm A Twin. Triplet, Actually. It's startling the amount of people who have no idea how me and my identical twin can be identical, but not the other twin.

posted on Sun, 10/31/2010 - 9:52am
Anonymous's picture
Anonymous says:

Hi, I have an identical twin brother. Growing up we were pretty much the same, had the same interests and such. When we started to grow up, I guess, we developed different personalities. I always hated wearing the same clothes as him, but my mother insisted, because she thought it was cute. Now, being an adult, we look different because we choose to. I tend to have longer hair, a beard, and am 10 lbs heavier than him. He usually has shorter hair, glasses, and is a bit thinner. But, if you were to make us look the same we would probably be harder to guess who is who? I tended to be, personality-wise, extroverted, while my twin was introverted. He had some depression and OCD growing up and lacked some social experience. While, I, was a trouble-maker and had more girlfriends. He was very creative and could draw very well. Where as I. was more logical and good at math and problem-solving (I got a 93% on the Navy ASVAB test) So, all in all, we have different personalities (we never tried to switch classes in school. I hated when people asked me that- it would have never worked), but are genetically almost an exact carbon clone of each other.

posted on Sat, 11/27/2010 - 11:23pm
Anonymous's picture
Anonymous says:

yeah my best friend is a identical twin but they have very slight diffrences like a few freckles her and not there

posted on Fri, 02/25/2011 - 5:24pm
Anonymous's picture
Anonymous says:

I'm a twin and my brother is so much better than me I am an identical twin and when he keeps winning I feel like I'm the weakling my best friends are twins to also identical I like the younger twin more because I'm the younger twin is it ok if I want to be myself

posted on Thu, 04/12/2012 - 8:58pm
Love Guru's picture
Love Guru says:

So maybe you lose because you expect to, think of your brother as your equal and things might start to improve. No matter what, remember your parents love you both the same. (:

posted on Sun, 04/15/2012 - 5:55pm

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