# Unique personal identifying features that cannot be mimicked **URL:** \ **Category:** Factual Questions\ **Created:** [July 2, 2016, 9:28pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955 "2016-07-02T21:28:45Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [July 2, 2016, 9:28pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/1 "2016-07-02T21:28:45Z")
So according to _Mission Impossible_, one’s walking gait is something that is uniquely personal identifying, can be verified by machine, and cannot be mimicked. That is, you cannot perfectly imitate the way someone else walks. We already know that one’s retinas are unique; one’s fingerprints are unique, and the frequency of one’s vocal cords are unique. And, of course, one’s DNA is unique. What other features does a person have that can be used to quickly verify their identity, with the right technology? ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [July 2, 2016, 10:10pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/2 "2016-07-02T22:10:11Z")
Ears. There is some thought that they are a better identifier than fingerprint (though it’s harder to find earprints at a crime scene). ---
**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:** [July 2, 2016, 10:21pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/3 "2016-07-02T22:21:13Z")
[Irises.](https://en.wikipedia.org/wiki/Iris_recognition) ---
**Author:** ![TipTapTwo](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@TipTapTwo](https://boards.straightdope.com/u/TipTapTwo)\ **Post date:** [July 2, 2016, 10:21pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/4 "2016-07-02T22:21:51Z")
Actually, fingerprints are not unique. Much like snowflakes, there is great variation, but researchers have found identical snowflakes before. Worse, police have found two people with the same fingerprints; Brandon Mayfield, a man from Oregon who never even went to Spain, was still sent to jail by the FBI because “top fingerprint experts said his prints were a perfect match for those found at the scene” (1:32-1:39) of the Madrid train bombings. Adam Ruins Everything - Why Fingerprinting Is Flawed Now brain scans are getting to be very reliable. With a success rate of "98–99% accuracy to pick out a brain scan of the same person — again at rest — on another day. But the predictive accuracy dropped to 80–90% when that person was performing a different cognitive task during the second session.” -Rachel Ehrenberg, Nature The interesting part is how a computer can learn how our individual brains prefer to think, our brain’s version of ‘handedness’ or ‘walking-gait,’ that is unique enough to highlight us out of a crowd of others, even when we are doing tasks unrelated to what the computer was fed as information to begin with. "The researchers were able to match the scan of a given individual’s brain activity during one imaging session to the same person’s brain scan taken at another time — even when that person was engaged in a different task in each session.” -Rachel Ehrenberg, Nature Brain scans pinpoint individuals from a crowd [http://www.nature.com/news/brain-scans-pinpoint-individuals-from-a-crowd-1.18541](http://www.nature.com/news/brain-scans-pinpoint-individuals-from-a-crowd-1.18541) ---
**Author:** ![Flyer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/flyer/32/7298_2.png) [@Flyer](https://boards.straightdope.com/u/Flyer)\ **Post date:** [July 2, 2016, 10:33pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/5 "2016-07-02T22:33:44Z")
The experts have never claimed that fingerprints are unique. Rather, they’ve said that for all practical purposes, fingerprints are unique. The figure I’ve always seen is a 1 out of 7 billion chance that two people would have identical fingerprints. ---
**Author:** ![pool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pool/32/4152_2.png) [@pool](https://boards.straightdope.com/u/pool)\ **Post date:** [July 3, 2016, 1:03am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/6 "2016-07-03T01:03:00Z")
I bet genitals are unique they should print those down at the police station. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [July 3, 2016, 6:28am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/7 "2016-07-03T06:28:05Z")
Identical twins also have identical DNA. ---
**Author:** ![Oakminster](https://avatars.discourse-cdn.com/v4/letter/o/77aa72/32.png) [@Oakminster](https://boards.straightdope.com/u/Oakminster)\ **Post date:** [July 3, 2016, 6:44am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/8 "2016-07-03T06:44:24Z")
I dispute the walking gait identifier. As an actor, at least for the short term, I can alter my natural gait as needed for whatever role I’m playing. That’s not a fixed physical characteristic so much as a choice made to suit a character. ---
**Author:** ![guizot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guizot/32/3636_2.png) [@guizot](https://boards.straightdope.com/u/guizot)\ **Post date:** [July 3, 2016, 6:58am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/9 "2016-07-03T06:58:35Z")
> [@Oakminster](#): > > I dispute the walking gait identifier. As an actor, at least for the short term, I can alter my natural gait as needed for whatever role I’m playing. That’s not a fixed physical characteristic so much as a choice made to suit a character. I would agree, though I’d also just mention that one of the subconscious ways that we recognize a person, especially from afar, is by their gait. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [July 3, 2016, 11:07am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/10 "2016-07-03T11:07:03Z")
> [@Flyer](#): > > The experts have never claimed that fingerprints are unique. Rather, they’ve said that for all practical purposes, fingerprints are unique. The figure I’ve always seen is a 1 out of 7 billion chance that two people would have identical fingerprints. I think some of the more problematic aspects of fingerprint identification is that they don’t necessarily match a whole print. They’ll put together fragments of latent fingerprints and look at small, distorted sections like putting together a puzzle, so while the odds may be seven billion to one against two people having the identical fingerprints is true, the odds against finding a partial fingerprint that matches a small part of someone’s fingerprint are much better. Here’s a document from the [Southern California Law Review](http://www.clpex.com/Information/USvMitchell/RobertEpstein/Robert_Epstein_CA_law%20Review.pdf). ---
**Author:** ![SmartAlecCat](https://avatars.discourse-cdn.com/v4/letter/s/67e7ee/32.png) [@SmartAlecCat](https://boards.straightdope.com/u/SmartAlecCat)\ **Post date:** [July 3, 2016, 11:45am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/11 "2016-07-03T11:45:36Z")
> [@Terminus\_Est](#): > > Identical twins also have identical DNA. And a single [chimera person](http://pictorial.jezebel.com/one-person-two-sets-of-dna-the-strange-case-of-the-hu-1689290862) can have two sets of DNA. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 3, 2016, 11:57am UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/12 "2016-07-03T11:57:58Z")
Identical twins also have fingerprints that are, while not completely identical, still very similar. ---
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [July 3, 2016, 12:59pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/13 "2016-07-03T12:59:47Z")
> [@guizot](#): > > I would agree, though I’d also just mention that one of the subconscious ways that we recognize a person, especially from afar, is by their gait. Or even the sound of their gait. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [July 3, 2016, 2:27pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/14 "2016-07-03T14:27:57Z")
> [@Oakminster](#): > > I dispute the walking gait identifier. As an actor, at least for the short term, I can alter my natural gait as needed for whatever role I’m playing. That’s not a fixed physical characteristic so much as a choice made to suit a character. While I doubt the veracity of the 'Mission Impossible" statement as well, your point supports that gait is used as an identifying feature (although NOT impossible to mimic). As a guy who couldn’t act his way out of a wet paper bag, I have to say it’s quite impressive how some actors can look like entirely different people just by changing how they carry themselves. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 3, 2016, 2:28pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/15 "2016-07-03T14:28:29Z")
I read somewhere, I think (or am just making this up), that the epithelial layers of our internal organs are consistent and unique. So there’s that. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [July 3, 2016, 3:55pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/16 "2016-07-03T15:55:14Z")
> [@Terminus\_Est](#): > > Identical twins also have identical DNA. [Nope.](http://www.scientificamerican.com/article/identical-twins-genes-are-not-identical/) ---
**Author:** ![chacoguy](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@chacoguy](https://boards.straightdope.com/u/chacoguy)\ **Post date:** [July 3, 2016, 6:10pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/17 "2016-07-03T18:10:04Z")
I believe that lip and tongue prints are unique. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 3, 2016, 6:13pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/18 "2016-07-03T18:13:09Z")
But by the same token, a single individual’s DNA is not identical, either. It’d be awfully tough to tell that way whether two samples came from a single person or from a pair of twins. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [July 3, 2016, 6:23pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/19 "2016-07-03T18:23:46Z")
> [@pool](#): > > I bet genitals are unique they should print those down at the police station. No, they just apply to the TSA to get a copy from them. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 3, 2016, 7:00pm UTC](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955/20 "2016-07-03T19:00:07Z")
> [@Leo\_Bloom](#): > > I read somewhere, I think (or am just making this up), that the epithelial layers of our internal organs are consistent and unique. > > So there’s that. > [@chacoguy](#): > > I believe that lip and tongue prints are unique. When it comes to that, barring plasticity of one sort or another, the crenellations of each of our brains is unique and relatively stable. It’s no more far-fetched for their to be non-invasive scanning as the idea of routine iris-scanning a generation or two ago. And less changeable by the individual than fingerprints or irises. [Next page](https://boards.straightdope.com/t/unique-personal-identifying-features-that-cannot-be-mimicked/758955.md?page=2)