# A question about identical twins **URL:** \ **Category:** Factual Questions\ **Created:** [April 9, 2010, 4:44am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498 "2010-04-09T04:44:28Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![AllFreedomUnlessDefyingScience](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@AllFreedomUnlessDefyingScience](https://boards.straightdope.com/u/AllFreedomUnlessDefyingScience)\ **Post date:** [April 9, 2010, 4:44am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/1 "2010-04-09T04:44:28Z")
Do identical twins also have identical navels? The reason I ask is that I had the impression that whether you have an ‘innie’ or and ‘outie’ are at least sometimes effected by environmental factors, i.e. what happens with the stump of the umbilical cord as it decays. Could someone give me the Straight Dope? Thanks for all replies, AllFree ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [April 9, 2010, 4:50am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/2 "2010-04-09T04:50:13Z")
No. The navel is basically a scar and as such is environmental, not genetic. In fact, differences in navels can be used to distinguish between identical twins. ---
**Author:** ![AllFreedomUnlessDefyingScience](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@AllFreedomUnlessDefyingScience](https://boards.straightdope.com/u/AllFreedomUnlessDefyingScience)\ **Post date:** [April 9, 2010, 4:52am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/3 "2010-04-09T04:52:19Z")
A definitive answer, thank you Colibri. If anyone has anything fun/interesting to add feel free. AllFree ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [April 9, 2010, 10:33am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/4 "2010-04-09T10:33:13Z")
In case you’re thinking about ways in which ‘identical’ twins are actually different from one another, there are at least two more: their [fingerprints](http://www.straightdope.com/columns/read/1277/do-identical-twins-have-different-fingerprints) and their [“repertoire” of antibodies](http://www.thedoctorweighsin.com/journal/2007/5/17/god-illuminated-how-immunity-works.html). ---
**Author:** ![ivan\_astikov](https://avatars.discourse-cdn.com/v4/letter/i/58f4c7/32.png) [@ivan\_astikov](https://boards.straightdope.com/u/ivan_astikov)\ **Post date:** [April 9, 2010, 10:41am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/5 "2010-04-09T10:41:15Z")
> [@KarlGauss](#): > > In case you’re thinking about ways in which ‘identical’ twins are actually different from one another, there are at least two more: their [fingerprints](http://www.straightdope.com/columns/read/1277/do-identical-twins-have-different-fingerprints) and their [“repertoire” of antibodies](http://www.thedoctorweighsin.com/journal/2007/5/17/god-illuminated-how-immunity-works.html). I can’t find it yet, but I’m sure I heard a story recently about a court case that was dismissed because a pair of twins had the same fingerprints. And I don’t think it was April the first when I heard it. I’ll keep looking. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [April 9, 2010, 11:15am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/6 "2010-04-09T11:15:25Z")
I’ve got a pair of hot identical twins coming round to my house on Sunday. I think I might ask to see their navels. ---
**Author:** ![China\_Guy](https://avatars.discourse-cdn.com/v4/letter/c/779978/32.png) [@China\_Guy](https://boards.straightdope.com/u/China_Guy)\ **Post date:** [April 9, 2010, 11:34am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/7 "2010-04-09T11:34:03Z")
identical twins arenLt identical genetically. IIRC, they are a 90%-ish match. Environmental factors in the womb and during birth can also reduce the identicalness ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 9, 2010, 1:04pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/8 "2010-04-09T13:04:56Z")
> [@China\_Guy](#): > > identical twins arenLt identical genetically. IIRC, they are a 90%-ish match. Would you care to elaborate on that? Because unless you’re talking about something I’ve never heard of, that’s completely wrong. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [April 9, 2010, 2:48pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/9 "2010-04-09T14:48:32Z")
> [@China\_Guy](#): > > identical twins arenLt identical genetically. IIRC, they are a 90%-ish match. Identical twins are clones, and while there may be some differences due to mutations or other anomalies they are very close to genetically identical. The 90% match doesn’t conform to anything I have ever heard either. Please clarify what kind of genetic differences you are talking about and the source of the 90% figures. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [April 9, 2010, 4:53pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/10 "2010-04-09T16:53:31Z")
> [@China\_Guy](#): > > identical twins arenLt identical genetically. IIRC, they are a 90%-ish match. Environmental factors in the womb and during birth can also reduce the identicalness Identical twins are the result of the fertilized egg splitting in two during early development. Each part goes on to develop into a separate person, but with identical chromosomes. Fraternal twins are the result of two eggs separately fertilized, and are no more related than any other two siblings - may even have separate fathers under the right(?) scenario. I’m not that up on my biology - the process of cell division creates (virtually) identical copies of the chormosomes. I don’t know if the split guarantees that evey cell gets a copy of all the mitochrondrial(?) DNA, those little rings of DNA fragments that are in the egg and inherited from the mother. So there could be a difference there. DNA does change over time due to replication accidents, etc. However, it’s nowhere near 10%; heck, the amount we differ in DNA from chimps and apes is, IIRC, close to zero. (less than 5%?) I have also read that identical twins have different fingerprints, since this is a developmental accident of which cells replicate how fast during gestation. If there was even the remte possibility that they were the same, you would have seen some use of that in CSI or Law & Order. God knows the twin-DNA thing has happened often enough. FWIW, I know a pair of identical twins where one is gay and the other has 4 children. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [April 9, 2010, 5:09pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/11 "2010-04-09T17:09:20Z")
> [@md2000](#): > > Identical twins are the result of the fertilized egg splitting in two during early development. Each part goes on to develop into a separate person, but with identical chromosomes. Fraternal twins are the result of two eggs separately fertilized, and are no more related than any other two siblings - may even have separate fathers under the right(?) scenario. > > I’m not that up on my biology - the process of cell division creates (virtually) identical copies of the chormosomes. I don’t know if the split guarantees that evey cell gets a copy of all the mitochrondrial(?) DNA, those little rings of DNA fragments that are in the egg and inherited from the mother. So there could be a difference there. > > DNA does change over time due to replication accidents, etc. However, it’s nowhere near 10%; heck, the amount we differ in DNA from chimps and apes is, IIRC, close to zero. (less than 5%?) > > I have also read that identical twins have different fingerprints, since this is a developmental accident of which cells replicate how fast during gestation. If there was even the remte possibility that they were the same, you would have seen some use of that in CSI or Law & Order. God knows the twin-DNA thing has happened often enough. > \*\* > FWIW, I know a pair of identical twins where one is gay and the other has 4 children\*\*. (bolding mine) So what? The two states are not mutually exclusive, y’know. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 9, 2010, 5:17pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/12 "2010-04-09T17:17:48Z")
[Retinal scans](http://en.wikipedia.org/wiki/Retinal_scan) and [iris recognition](http://en.wikipedia.org/wiki/Iris_recognition) supposedly would reveal differences, too. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [April 9, 2010, 5:21pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/13 "2010-04-09T17:21:31Z")
> [@purplehorseshoe](#): > > (bolding mine) > > So what? The two states are not mutually exclusive, y’know. I agree. The condition is likely developmentally rather than genetically determined. An interesting factoid. ---
**Author:** ![ivan\_astikov](https://avatars.discourse-cdn.com/v4/letter/i/58f4c7/32.png) [@ivan\_astikov](https://boards.straightdope.com/u/ivan_astikov)\ **Post date:** [April 9, 2010, 7:00pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/14 "2010-04-09T19:00:55Z")
I couldn’t find that recent news story, but I did find this. [The Myth Of Fingerprints](http://books.google.co.uk/books?id=jg8AAAAAMBAJ&pg=PA44&lpg=PA44&dq=case+dismissed+because+twins+have+same+fingerprints&source=bl&ots=3gJGDkTdwr&sig=gD4lgs6eouKg1OfYRLzzJ94Y1sE&hl=en&ei=CA6_S9W8Lpn40wSVjqGaCQ&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAsQ6AEwAQ#v=onepage&q&f=false) Does anyone want to contest what is wrote in that article? ---
**Author:** ![Mk\_VII](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)\ **Post date:** [April 9, 2010, 8:30pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/15 "2010-04-09T20:30:53Z")
The Fox brothers were a pair of identical twins in 19th c. England who were partners in crime. One would make himself prominent in a town far off while the other committed crimes. If arrested each would blame the other and as no one could say which was which the prosecution failed. They were identified by fingerprints, possibly the first case in England where this was admitted as evidence. > **[Albert and Ebenezer Fox](https://en.wikipedia.org/wiki/Albert_and_Ebenezer_Fox)** > > Albert Ebenezer Fox (1857 – 20 May 1937) and Ebenezer Albert Fox (1857 – 2 October 1926) were infamous English poachers who lived in Stevenage in the late 19th and early 20th centuries. They were identical twins and were also known as the Twin Foxes. > They were born in 1857 in Symonds Green and named after the Ebenezer Chapel (Baptist Church) on Albert Street, of which their father, Henry Fox, was a devout supporter. Their mother, Charlotte Fox, was a straw-plait worker and their father farmed ... The Shirley McKie case in Scotland was one which turned solely on fingerprint identification, and was essentially about whether a police officer was telling the truth or not, and whether fingerprint identification was incontrovertible or not. > **[Shirley McKie](https://en.wikipedia.org/wiki/Shirley_McKie)** > > Shirley McKie (born August 1962) is a former Scottish police detective who was accused by fingerprint analysis staff of the Scottish Criminal Record Office (SCRO) of leaving her thumb print on the bathroom door frame of a murder crime-scene in Kilmarnock on 14 January 1997. > She denied she had ever been in the house of murder victim Marion Ross, but Detective Constable McKie was initially suspended, then sacked, then arrested by Strathclyde Police in 1998, and tried and acquitted in 1999. A sc... ---
**Author:** ![Fiveroptic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiveroptic/32/8257_2.png) [@Fiveroptic](https://boards.straightdope.com/u/Fiveroptic)\ **Post date:** [April 10, 2010, 6:03pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/16 "2010-04-10T18:03:02Z")
> [@md2000](#): > > FWIW, I know a pair of identical twins where one is gay and the other has 4 children. Anecdotally, my two oldest nieces are identical twins, and both are without doubt, lesbians. Their three younger siblings are quite straight. All five siblings have Masters Degrees and/or are working on their doctorates. This has nothing to do with anything, of course, but I’m very proud of them and like to mention what good kids they are whenever possible. 🙂 ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [April 11, 2010, 7:33pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/17 "2010-04-11T19:33:15Z")
> [@ivan\_astikov](#): > > I couldn’t find that recent news story, but I did find this. [The Myth Of Fingerprints](http://books.google.co.uk/books?id=jg8AAAAAMBAJ&pg=PA44&lpg=PA44&dq=case+dismissed+because+twins+have+same+fingerprints&source=bl&ots=3gJGDkTdwr&sig=gD4lgs6eouKg1OfYRLzzJ94Y1sE&hl=en&ei=CA6_S9W8Lpn40wSVjqGaCQ&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAsQ6AEwAQ#v=onepage&q&f=false) > > Does anyone want to contest what is wrote in that article? So you make an outlandish assertion, can’t back it up, come up with an unrelated article on fingerprints, and then dare us to challenge _that_? Better get back to your Jew baiting; you seem to do better at that. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [April 11, 2010, 8:26pm UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/18 "2010-04-11T20:26:31Z")
> [@KarlGauss](#): > > Better get back to your Jew baiting; you seem to do better at that. [Moderator Note] Dragging in some unrelated matter to attack another poster is not appropriate for GQ. No warning issued, but don’t do this again. Colibri General Questions Moderator ---
**Author:** ![flodnak](https://avatars.discourse-cdn.com/v4/letter/f/838e76/32.png) [@flodnak](https://boards.straightdope.com/u/flodnak)\ **Post date:** [April 12, 2010, 6:27am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/19 "2010-04-12T06:27:11Z")
> [@KarlGauss](#): > > In case you’re thinking about ways in which ‘identical’ twins are actually different from one another, there are at least two more: their [fingerprints](http://www.straightdope.com/columns/read/1277/do-identical-twins-have-different-fingerprints) and their [“repertoire” of antibodies](http://www.thedoctorweighsin.com/journal/2007/5/17/god-illuminated-how-immunity-works.html). And, of course, other mostly-environmental marks like birthmarks and moles. News reporters apparently used a mole on the late Polish President Kazcynski’s cheek to distinguish him from his identical twin brother (who is the Prime Minister and therefore _also_ often in the spotlight). Coincidentally that’s also how I distinguish two of my younger son’s best friends, who are identical twins: one has a mole on his cheek and the other doesn’t. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [April 12, 2010, 6:54am UTC](https://boards.straightdope.com/t/a-question-about-identical-twins/535498/20 "2010-04-12T06:54:03Z")
> [@md2000](#): > > Identical twins are the result of the fertilized egg splitting in two during early development. Each part goes on to develop into a separate person, but with identical chromosomes. Fraternal twins are the result of two eggs separately fertilized, and are no more related than any other two siblings - may even have separate fathers under the right(?) scenario. While MZ (monozygotic) twins have identical DNA, epigenetic factors (ie external chemical modifiers that attach to DNA influencing gene expression) can cause differences in development over time. These sorts of changes are more likely to diverge significantly when twins experience environmental variation or illness. [Cite](http://ec.europa.eu/research/headlines/news/article_05_07_27_en.html). I doubt that this adds up to a 10% difference in expression, though. Si [Next page](https://boards.straightdope.com/t/a-question-about-identical-twins/535498.md?page=2)