# If identical twins have the same DNA, why are their finger prints different? **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2004, 10:55pm UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673 "2004-05-17T22:55:23Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![SallyStar](https://avatars.discourse-cdn.com/v4/letter/s/a3d4f5/32.png) [@SallyStar](https://boards.straightdope.com/u/SallyStar)\ **Post date:** [May 17, 2004, 10:55pm UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/1 "2004-05-17T22:55:23Z")
If identical twins have the same DNA, why do they have different finger prints? Anything else different? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [May 17, 2004, 11:08pm UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/2 "2004-05-17T23:08:58Z")
Because fingerprints are part of the phenotype, not the genotype. There’s a lot to say on the matter, but in short, your genotype is what genes you have, and your phenotype is what gets built from those genes. Obviously, the genetic code doesn’t completely determine details like that, so there’s some room for variation. A biologist can explain at greater detail. ---
**Author:** ![1010011010](https://avatars.discourse-cdn.com/v4/letter/1/ea666f/32.png) [@1010011010](https://boards.straightdope.com/u/1010011010)\ **Post date:** [May 17, 2004, 11:14pm UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/3 "2004-05-17T23:14:03Z")
Think of it like snowflakes. All snowflakes are made of water, so they should all be identical, right? The proteins that directed the patterns of their fingerprints “crystalized” differently, as did any number of other things on the piddling detail level. For another analogy, imagine a school ochestra. One year, the conductor has them play Beethoven’s 5th. A few year later, with a completely different set of students, the same conductor has them play Beethoven’s 5th again. Though you’d easily be able to recognize the two performances as being the same (say, identical, even), there will still be differences. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 17, 2004, 11:32pm UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/4 "2004-05-17T23:32:19Z")
You, as an organism, are made up of the interactions between your genes and your environment. More specifically, making fingerprints is a partially random process, so you’re going to get different results from identical starting positions. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 18, 2004, 1:16am UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/5 "2004-05-18T01:16:00Z")
A similar situation has occurred in cloning. Both kitties and horses have been cloned, and the result has been that although the DNA was identical, they had the same colors–but not the same color patterns. ---
**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:** [May 18, 2004, 1:40am UTC](https://boards.straightdope.com/t/if-identical-twins-have-the-same-dna-why-are-their-finger-prints-different/245673/6 "2004-05-18T01:40:43Z")
I read, but cannot provide a reference off hand, to the effect that fingerprint patterns are the result of physical processes within the amniotic fluid, eg. various fluid and pressure waves. Since there is always asymmetry in such processes within the womb, it means that even identical twins will have different fingerprints.