# Do identical twins have identical genitalia?
**URL:** https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211
**Category:** Factual Questions
**Created:** [July 27, 2006, 3:39am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211 "2006-07-27T03:39:34Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@diggleblop](https://boards.straightdope.com/u/diggleblop)
#### Post date: [July 27, 2006, 3:39am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/1 "2006-07-27T03:39:34Z")
Do they have identical genitalia
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### Author:  [@TJdude825](https://boards.straightdope.com/u/TJdude825)
#### Post date: [July 27, 2006, 4:02am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/2 "2006-07-27T04:02:34Z")
If you eat all your vegetables and grow up big and strong, will, um, it grow too? If so, the answer is no.
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### Author:  [@diggleblop](https://boards.straightdope.com/u/diggleblop)
#### Post date: [July 27, 2006, 4:08am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/3 "2006-07-27T04:08:14Z")
cite?
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [July 27, 2006, 4:16am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/4 "2006-07-27T04:16:05Z")
To the extent that appearance of genitalia is genetic, yes. To the extent that they can be modified by environmental influences, no. As an example, if one of two male twins is circumcized, and the other is not, then their genitalia are going to look significantly different.
Could you perhaps provide a bit more context? As it is, the answer seems too obvious.
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### Author:  [@diggleblop](https://boards.straightdope.com/u/diggleblop)
#### Post date: [July 27, 2006, 4:17am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/5 "2006-07-27T04:17:47Z")
Do two identical females have identical looking vulvas? Meaning, they can’t be told apart if you were to take a picture of each. Would the two look exactly alike?
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### Author:  [@Colibri](https://boards.straightdope.com/u/Colibri)
#### Post date: [July 27, 2006, 4:18am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/6 "2006-07-27T04:18:24Z")
Identical twins, while genetically identical, are not necessarily completely identical physically. Development can affect their physical appearance. For example, identical twins have different fingerprints.
Generally, their genitalia should be just as similar, on average, as any other part of their anatomies. However, in some cases identical twins would be expected to differ in this, just as they would in any other aspect.
Why do you ask? Are you dating a twin, and wondering if they are pulling a fast one on you?
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### Author:  [@diggleblop](https://boards.straightdope.com/u/diggleblop)
#### Post date: [July 27, 2006, 4:26am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/7 "2006-07-27T04:26:58Z")
ha, I _wish_ I was dating a twin. I’ve just always wondered this and have never really had the pleasure of finding out on my own yet.
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### Author:  [@Colibri](https://boards.straightdope.com/u/Colibri)
#### Post date: [July 27, 2006, 4:28am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/8 "2006-07-27T04:28:08Z")
Apply for a grant.
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### Author:  [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)
#### Post date: [July 27, 2006, 4:39am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/9 "2006-07-27T04:39:30Z")
Isn’t genital size (and presumably other characteristics, like luminosity) determined largely by hormonal changes at adolescence? I wouldn’t expect twins to automatically undergo these changes at precisely the same rate because of environmental factors too numerous to track.
[This PDF file](http://genepi.qimr.edu.au/staff/nick_pdf/CV285.pdf) shows that height is also slightly variable between twins, with a correlation for identical males at 0.91 ± 0.01 and identical females at 0.92 ± 0.01. High, but not perfect. It’s not implausible that genitalia show similar variation, though you might have to break out the calipers to verify it.
And if you _are_ dating a twin, you can always surreptitiously use a magic marker to place a dot in some unobvious place, if you think the ol’ switcheroo is being pulled. Personally, I’d try to get them both at once.
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### Author:  [@silenus](https://boards.straightdope.com/u/silenus)
#### Post date: [July 27, 2006, 5:12am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/10 "2006-07-27T05:12:31Z")
Luminosity? Like, glow-in-the-dark balls? ¿Que?
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### Author:  [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)
#### Post date: [July 27, 2006, 5:16am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/11 "2006-07-27T05:16:29Z")
> [@silenus](#):
>
> Luminosity? Like, glow-in-the-dark balls? ¿Que?
Oh. Maybe it’s just me.
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### Author:  [@Chez\_Guevara](https://boards.straightdope.com/u/Chez_Guevara)
#### Post date: [July 27, 2006, 5:32am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/12 "2006-07-27T05:32:24Z")
> [@silenus](#):
>
> Luminosity? Like, glow-in-the-dark balls? ¿Que?
_cough_
> [@](#):
>
> I have received in the mail a Christmas Catalogue from a company called Faux Ballons. This supplier is the Major Player in the Plastic Testicle arena, and has just revamped its product range to reflect the changing nature of the marketplace.
>
> Customers can now buy Faux Ballons products with an option to have one inserted into the Scrotal Sac in the usual way, or they can have an Orb which attaches to the Ear as a fashion accessory (warning: Ears must be pierced first).
>
> The Ballons are sold either singly or in a boxed set of 3 and, in an exciting new development, they are now available in the colours of your favourite football team.
>
> With Christmas just around the corner, it’s worth mentioning that there is no need to use expensive wrapping paper on these products. They can be attached to any Christmas Tree so as to be indistinguishable from other ornamentation, especially if covered with a light coating of Glitter.
>
> The piece de resistance in the Faux Ballon range is the Illuminated Testicle (batteries not included) which flashes on and off in time with the Christmas Tree lights.
>
> If the fortunate recipient of this item chooses to have it installed in the Scrotum, it should prove extremely useful when walking home in the dark naked, since oncoming traffic will be alerted to the recipient’s presence thus preventing Nasty Accidents.
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### Author:  [@alphaboi867](https://boards.straightdope.com/u/alphaboi867)
#### Post date: [July 27, 2006, 5:48am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/13 "2006-07-27T05:48:59Z")
> [@Chronos](#):
>
> … As an example, if one of two male twins is circumcized, and the other is not, then their genitalia are going to look significantly different…
I knew a set of twins in high school who’s parents did just that! Apparntly they wanted a easy foolproof way of telling them apart.
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### Author:  [@chorpler](https://boards.straightdope.com/u/chorpler)
#### Post date: [July 27, 2006, 10:45am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/14 "2006-07-27T10:45:58Z")
I asked my wife, whose tales of her family have often been shocking to my delicate Mormon-raised ears with their forthrightness about bodily and sexual matters (“Your MOM bought you guys a PLAYGIRL when you told her neither of you had ever seen a PENIS?!”, etc.), if she and her twin sister have identical vulva/labia/vaginal areas. She said “Um, I don’t know.” I said “But your family has no problem with nudity. You must have seen hers!” And she looked at me and said “Yeah, uh, sadly, you’re mistaken if you think that walking to our bedroom after a shower meant that we sat around spreading our legs and looking at each others genitals.”
So clearly I’ll need to have an videotaped affair with her sister to answer this question. It’s rough work, but somebody has to get reliable documentation on these things for science.
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### Author:  [@Jonathan\_Chance](https://boards.straightdope.com/u/Jonathan_Chance)
#### Post date: [July 27, 2006, 10:51am UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/15 "2006-07-27T10:51:39Z")
> [@Colibri](#):
>
> Apply for a grant.
Best scientist answer, ever.
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### Author:  [@Colibri](https://boards.straightdope.com/u/Colibri)
#### Post date: [July 27, 2006, 2:55pm UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/16 "2006-07-27T14:55:02Z")
> [@Jonathan Chance](#):
>
> Best scientist answer, ever.
Yes, I feel certain this is an open area for investigation.
🙂
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### Author:  [@Cervaise](https://boards.straightdope.com/u/Cervaise)
#### Post date: [July 27, 2006, 3:13pm UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/17 "2006-07-27T15:13:40Z")
> [@diggleblop](#):
>
> Do two identical females have identical looking vulvas?
Not at all. In fact, given identical female twins, one of them will have a penis. But you should have asked about fraternal twins of different sexes; _they_ have identical genitalia.
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### Author:  [@yBeayf](https://boards.straightdope.com/u/yBeayf)
#### Post date: [July 27, 2006, 3:32pm UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/18 "2006-07-27T15:32:06Z")
> [@](#):
>
> Not at all. In fact, given identical female twins, one of them will have a penis. But you should have asked about fraternal twins of different sexes; they have identical genitalia.
The fuck?
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### Author:  [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)
#### Post date: [July 27, 2006, 3:42pm UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/19 "2006-07-27T15:42:11Z")
> [@](#):
>
> Plastic Testicle arena
Well, we now have a place for all those “Band name!” groups to perform in…
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### Author:  [@One\_And\_Only\_Wanderers](https://boards.straightdope.com/u/One_And_Only_Wanderers)
#### Post date: [July 27, 2006, 3:44pm UTC](https://boards.straightdope.com/t/do-identical-twins-have-identical-genitalia/366211/20 "2006-07-27T15:44:52Z")
> [@alphaboi867](#):
>
> I knew a set of twins in high school who’s parents did just that! Apparntly they wanted a easy foolproof way of telling them apart.
wonder how they decided who got the \… short straw
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