4 ms·

So before all of this, a crime would happen, you'd leave a fingerprint, the police attempt to match it with a fingerprint in their databases that you might have

by asdff 4y ago

So before all of this, a crime would happen, you'd leave a fingerprint, the police attempt to match it with a fingerprint in their databases that you might have had to submit to get a drivers license. All fine because people understand the science of fingerprinting. Today, a crime would happen, you leave DNA, the police attempt to match it with a DNA sample in their databases you might have submitted for a health screening. 4th amendment violation because DNA is scary to the lay person it seems. This is not from logical reasoning but from emotional reasoning, because for all intents and purposes DNA databases are being used exactly like fingerprint databases that are normalized in our society today, and shouldn't actually have this scrutiny (or maybe fingerprints should have more scrutiny if you are against DNA screening for crimes, because the logical arguments would be the same). Then again these articles generate clicks while I'm sure most would eyeroll a fingerprinting article.

giantg2 4y ago
Considering the quality of the labs performing the work, every test deserves scrutiny.
- asdff 4y ago
  But its not being argued on that angle, its being argued on a 4th amendment angle. If it were being argued on that angle, why not also scrutinize the state fingerprinting labs on that same argument? They don't get that scrutiny though. It's just mainly a fear of DNA technology owing to privacy concerns, not really due to concerns that the sample could be crosscontaminated or that the labs aren't qualified to perform the work. Neither were mentioned in the article anyhow, just the 4th amendment angle.
  - giantg2 4y ago
    Sure, that wasn't mentioned in the article because it's not specific to DNA tests, but all tests. The difference with DNA is that the genetic data has a ton of info associated with it, and that in this case it was collected for healthcare purposes. Fingerprints don't carry sensitive health data. The arguments are different.
    - asdff 4y ago
      The health data is not being used for criminology purposes. Only the pattern of the DNA so yes its like using the pattern of your fingerprint or even your iris or other sources of unique biologically identifiable material you have on your person.
      - giantg2 4y ago
        Did you read what you wrote? The pattern is the health data...
  - Beltalowda 4y ago
    I looked into this a bit some time ago, and fingerprint matching is significantly more error-prone and "fuzzy" than DNA matching. In that sense the argument against fingerprint databases is, IMHO, a lot of better than that against DNA databases. There are some other differences too though: you're much more in control over where you leave your fingerprints than where you leave your DNA and fingerprints are not connected to your relatives. Not leaving any traces of your DNA is essentially almost impossible. What concerns me that is people might be hesitant to do this blood screening for their newborns if they were ever involved in a crime, even a minor one, which would negatively impact their (innocent) newborns. With fingerprints you can be reasonably sure you didn't leave them with pretty basic precautions, and you don't need to fear your children's fingerprints fingering you in the first place. With DNA that's quite different. So I'm not so sure the trade-off is worth it here, except for some of the most serious crimes.
    - asdff 4y ago
      Appeals to ignorance or bad intentions are not good arguments to do away with a good system that simultaneously leads to improved public health and rapists in jail IMO. If people are avoiding it and its leading to poorer outcomes for those newborns with criminal parents, then all the more reason to make this sort of screening mandatory, much like how its a good idea to mandate vaccinations even if it steps on the toes of the poorly informed in the process.
      - Beltalowda 4y ago
        I don't think it's an "appeal or ignorance" at all. Furthermore, the story has an example of DNA from a rapekit being used to solve a years-old burglary. That doesn't strike as a good trade-off to me. The parents may no longer be criminals; they may have done a few stupid things when they were 18 or whatnot. Not excusing it, but also don't need to go above and beyond any lengths to solve these comparatively minor crimes: literally no one is served by that: not the victims of the crime, not society, and certainly not their children. In more serious crimes, it may be worth the trade-off – that I why I used the qualifier "except for some of the most serious crimes". > make this sort of screening mandatory, much like how its a good idea to mandate vaccinations even if it steps on the toes of the poorly informed in the process. It's not realistic this will be enacted any time soon, if ever, and any proposal needs to take this political reality in to account.
  - anigbrowl 4y ago
    Police can't figure out your parent's fingerprint from looking at your fingerprint. Only 4 states collect fingerprints from driver's licenses; California does so only to do a background check for certain kinds of vehicle industry occupational licensing. Also applying for a license means you are at or approaching the age of majority. Either you are applying for a license knowing that you once did a crime, or you're doing a crime knowing you once submitted a fingerprint for a license. That's very different from having your blood sampled as a newborn, and most people assume their health information had privacy protection. Apples and oranges are both fruits, but they're not interchangeable.
phkahler 4y ago
DNA can be used to verify a suspect, it is not really valid to compare a crime scene sample to a national database because you WILL get a match with high probability even if the perp is not in the database. DNA is not a unique identifier, at least no the way its used. In this case it sounds like they used it for verification, since the sought a comparison of a suspect with a specific baby's DNA. From a science perspective this seems quite reasonable. From a privacy PoV IDK.
- dekhn 4y ago
  In the way that it's used, DNA is as close to a unique identifier as you can get. There are many techniques. https://en.wikipedia.org/wiki/DNA_profiling https://en.wikipedia.org/wiki/DNA_profiling You can tune the stringency but they shouldn't be causing enough false positives that screening will just turn up random people. More likely to get close relatives of people in the room at some point. See "partial matching" on the linked page.
tablespoon 4y ago
> police attempt to match it with a fingerprint in their databases that you might have had to submit to get a drivers license Where is this required? Because I've never heard of such a thing in the US.
- asdff 4y ago
  They printed me in California at least.
- hoistbypetard 4y ago
  I've had licenses in NC, MA and VA. None of those required fingerprints.
- s1artibartfast 4y ago
  you need one on file for a drivers license in California. I didnt want to give it due to privacy, but well... I have to drive so here I am
impossiblefork 4y ago
It's very much logical reasoning, and it's not about DNA being scary. It's about a kind of perfidy. It's the reason you in war don't masquerade as someone who is wounded and to try to get at your enemy, and don't use fake medical stuff in ruses, &c (this of course happened once in Pakistan, but I count it as those responsible lacking in understanding and being short-sighted). You don't ever do anything that will in any way affect people's trust in the medical system, even indirectly. This has been understood for a long time, and is part of the reason why the Hippocratic oath (i.e. the actual Hippocratic oath) involves swearing to never do any harm.
tunesmith 4y ago
> the police attempt to match it with a DNA sample in their databases you might have submitted for a health screening. I know you were attempting to draw a parallel, but the difference is that the DMV is a government organization (part of the DOT), and your medical provider is not. There are different expectations of privacy. Which is close to the heart of the issue.
- asdff 4y ago
  Your medical provider provides plenty of information to the state at their behest as it is. Chances are that started with your birth when your birth certificate was made official. Sensitive medical information is not being used to solve crimes here, they aren't looking for people with certain conditions etc. They are asking if a sample matches another sample in a database and to what proportion they are in agreement. That's it.
salawat 4y ago
Law enforcement is using Third Party Doctrine and usage of non LE DNA databases to work around the requirement for probable cause. As I understand it, public health regulations are exacerbating the availability of this data by mandating submittal of DNA for screening, and retaining the data. There is also the CSI effect to take into account and once again, the bloody fact we don't need to be preserving this data in perpetuity. This is why Third Party Doctrine is a complete and total deconstruction of the 4th Amendment in practice.
- asdff 4y ago
  It would be a huge scientific loss to discard collected genetic material. We should be cataloging all DNA that we can, not just from humans but from crops we grow and ecological marker species that proxy ecosystem health. You never know if there will be some test uncovered in the future that you could use against these previously collected samples and make some life saving inferences. When you throw that data away, you've eliminated that possibility forever and damned future scientists.
criddell 4y ago
If you collect my DNA you're getting a whole lot more information about me than you would from a fingerprint. I guess it depends on how the DNA is stored. If it's an opaque hash, then I probably agree with you. I'd hate to become a suspect in a crime because of some profile worked up by a behavioral analyst at the FBI and something in my DNA suggests I could fit the profile.
- asdff 4y ago
  Well, that's not how its really used per say. They aren't looking for behavioral features, they are looking for pattern matches not unlike a fingerprint. The advantage of this versus a fingerprint is the heritability aspect. You share half your DNA with either parent and you can proportionally estimate degree of shared dna for relatives in a geneology. That means they don't have to make sure the killer is in the finger print database, a distant relative and some math can in practice expand your database.
  - criddell 4y ago
    > They aren’t looking for behavioral features. I might be on board if you could make the stronger claim that they can’t look for behavioral features nor will they be able to in the future. A good hash provides that guarantee.
    - asdff 4y ago
      The argument is that they aren't considering phenotype information when they are solving crimes. How would that information even be used? A lawyer would have a stronger argument arguing a predisposition to criminality on environmental factors: a broken home, being raised when leaded gas was used, etc, versus arguing in terms of genetic association. These studies are not very robust connecting behavior and genetics because environment is a huge factor that explains the observed variances in these phenotypes. That being said, these data are being used for actually legally actionable things: first order pattern recognition using the same legal frameworks as fingerprints. Not second order "what do these patterns actually do in the body" or third order "what do these functions in the body do for the individual", each of which would probably take a PhD project to work out.
gopalv 4y ago
> 4th amendment violation because DNA is scary to the lay person it seems. There's probably a curve where it gets scary again as you know more about it. DNA isn't just identification. It is a lot more than just a unique identifier, it is a whole history and a lot of future probabilities. My list of SNPs is a lot less "if you have nothing to hide" about it. Imagine a government which looks at SCN1/SCN2 before issuing a drivers license.
- pc86 4y ago
  Is there a genetic component to being a skilled and/or safe driver? Society as a whole would probably be a lot better off if we stopped pretending driving around 4,000-lb hunks of metal at 80mph/130kph was some sort of inalienable right and actually showed some discretion in who was allowed to do it and who wasn't. But it's not realistic, especially if you live outside of a city.
- asdff 4y ago
  Well the government is not doing that in this case. They don't care about phenotypes for this analysis. The phenotypes are used for other analysis like public health efforts, but for law enforcement they just ask whether one pattern matches another and to what proportion it matches, and then if it matches a psuedorelative they go about to see if there is infact a person who could be this psuedorelative, then they go about and see if the person did commit the crime with other pieces of evidence.
crote 4y ago
There are two issues here. First, you constantly leave DNA everywhere. You are literally shedding it, even when you are not committing a crime. It is _guaranteed_ that DNA of innocent people ends up at crime scenes. While it is certainly useful at _confirming_ a suspect, it is way less powerful when trying to _find_ a suspect. Second, DNA matching is a matter of chance. While comparing a sample to a single potential match is extremely reliable, comparing a sample to a population is not. You're basically running into a birthday paradox here: given a large enough dataset, false matches are guaranteed to happen. If you use biometrics databases like this, you basically end up reverting the burden of proof: your DNA was at the crime scene, can you explain how it got there if you are indeed innocent?
- asdff 4y ago
  It's not exactly a birthday paradox because you have way more than 365 potential variants. Some 324 million. Plus its not discrete variants like having a single date of birth, you can have multiple combinations of variants. But broadly the big utility is in matching distant relatives versus strangers from the lot, and seeing if there is agreement with those putative matches with actual records and other hard evidence. You share half your DNA with either parent, 1/8 with your first cousin, and so on and so fourth for the rest of the human race. Using that information coupled with other pieces of evidence can yield a pretty reliable hit and is how they managed to catch the Golden State killer using DNA and genealogy.
- xboxnolifes 4y ago
  Does everything you just said not also apply to fingerprints? You leave them everywhere you touch, and people touch a lot of things. Maybe less so than DNA, since it's effectively a subset (things you touch likely have DNA from your hand skin, but things you don't touch might also have DNA from other things), but it's still just saying "you were likely here". And given a large enough population, wouldn't there also be many partial fingerprint matches? I'm not sure how these two things are issues when comparing fingerprinting to DNA matching. They seem to be applicable to both.
yetanotherloser 4y ago
Given the surprisingly poor perfection of dna "matching" and the tendency for public and law-court rhetoric to seriously misrepresent the odds of a mistake... at this point anyone who would voluntarily submit dna - or anything other than fight very hard against handing it over - has grotesquely poor judgement.
- asdff 4y ago
  Can you site a source documenting this poor perfection of DNA matching? I dug into this after reading your comment and I found the opposite was true, that a false positive as an odds on the rate of 1 in 1 billion. When you couple it with the fact you also need more than just DNA evidence to convict (which was done with the golden state killer, DNA was not the only source of evidence), the odds grow even smaller of 1) you having no alibi or potentially being at the place of the crime at the time and more evidence, and 2) you being that 1 in 1 billion match to the real killer. https://www.parliament.uk/documents/post/postpn258.pdf https://www.parliament.uk/documents/post/postpn258.pdf
  - yetanotherloser 4y ago
    pop article and still too forgiving, but this is not a bad start: https://freakonomics.com/2008/08/are-the-fbis-probabilities-about-dna-matches-crazy/ https://freakonomics.com/2008/08/are-the-fbis-probabilities-... (it's still excessively charitable about the odds because the genetic factors are not really perfectly independent and even a tiny bit of interdependence wreaks havoc with large probability calculations) The link you cite with "1 in billions" odds is exactly the sort of misrepresentation I'm talking about. Combine smaller-than-pretended probabilities with big database trawling and it becomes a bit like the "birthday problem": it provides really good odds of finding someone to pin the crime on, but very little confidence that it was really them.
    - asdff 4y ago
      The birthday problem is different because there are 365 possibilities and every individual can only have 1 out of 365 states. For DNA there are over 300 million variants in the human genome and you can have different combinations of these variants. As far as matching 9 of 13 loci, thats not surprising to me nor concerning. If you left a sample at a crime scene it would match all 13 loci. Today the FBI uses at least 20 loci. On top of that, merely being a dna match does not mean you are going to jail. You need corroborating evidence just like how finger prints are used. The odds of a false positive that 1) is a dna match and 2) was in the right place at the right time and lacks and alibi and has a potential motive for the crime must be a trillion to one.

by asdff 4y ago

giantg2 4y ago

Considering the quality of the labs performing the work, every test deserves scrutiny.

asdff 4y ago
But its not being argued on that angle, its being argued on a 4th amendment angle. If it were being argued on that angle, why not also scrutinize the state fingerprinting labs on that same argument? They don't get that scrutiny though. It's just mainly a fear of DNA technology owing to privacy concerns, not really due to concerns that the sample could be crosscontaminated or that the labs aren't qualified to perform the work. Neither were mentioned in the article anyhow, just the 4th amendment angle.
- giantg2 4y ago
  Sure, that wasn't mentioned in the article because it's not specific to DNA tests, but all tests. The difference with DNA is that the genetic data has a ton of info associated with it, and that in this case it was collected for healthcare purposes. Fingerprints don't carry sensitive health data. The arguments are different.
  - asdff 4y ago
    The health data is not being used for criminology purposes. Only the pattern of the DNA so yes its like using the pattern of your fingerprint or even your iris or other sources of unique biologically identifiable material you have on your person.
    - giantg2 4y ago
      Did you read what you wrote? The pattern is the health data...
- Beltalowda 4y ago
  I looked into this a bit some time ago, and fingerprint matching is significantly more error-prone and "fuzzy" than DNA matching. In that sense the argument against fingerprint databases is, IMHO, a lot of better than that against DNA databases. There are some other differences too though: you're much more in control over where you leave your fingerprints than where you leave your DNA and fingerprints are not connected to your relatives. Not leaving any traces of your DNA is essentially almost impossible. What concerns me that is people might be hesitant to do this blood screening for their newborns if they were ever involved in a crime, even a minor one, which would negatively impact their (innocent) newborns. With fingerprints you can be reasonably sure you didn't leave them with pretty basic precautions, and you don't need to fear your children's fingerprints fingering you in the first place. With DNA that's quite different. So I'm not so sure the trade-off is worth it here, except for some of the most serious crimes.
  - asdff 4y ago
    Appeals to ignorance or bad intentions are not good arguments to do away with a good system that simultaneously leads to improved public health and rapists in jail IMO. If people are avoiding it and its leading to poorer outcomes for those newborns with criminal parents, then all the more reason to make this sort of screening mandatory, much like how its a good idea to mandate vaccinations even if it steps on the toes of the poorly informed in the process.
    - Beltalowda 4y ago
      I don't think it's an "appeal or ignorance" at all. Furthermore, the story has an example of DNA from a rapekit being used to solve a years-old burglary. That doesn't strike as a good trade-off to me. The parents may no longer be criminals; they may have done a few stupid things when they were 18 or whatnot. Not excusing it, but also don't need to go above and beyond any lengths to solve these comparatively minor crimes: literally no one is served by that: not the victims of the crime, not society, and certainly not their children. In more serious crimes, it may be worth the trade-off – that I why I used the qualifier "except for some of the most serious crimes". > make this sort of screening mandatory, much like how its a good idea to mandate vaccinations even if it steps on the toes of the poorly informed in the process. It's not realistic this will be enacted any time soon, if ever, and any proposal needs to take this political reality in to account.
- anigbrowl 4y ago
  Police can't figure out your parent's fingerprint from looking at your fingerprint. Only 4 states collect fingerprints from driver's licenses; California does so only to do a background check for certain kinds of vehicle industry occupational licensing. Also applying for a license means you are at or approaching the age of majority. Either you are applying for a license knowing that you once did a crime, or you're doing a crime knowing you once submitted a fingerprint for a license. That's very different from having your blood sampled as a newborn, and most people assume their health information had privacy protection. Apples and oranges are both fruits, but they're not interchangeable.

phkahler 4y ago

DNA can be used to verify a suspect, it is not really valid to compare a crime scene sample to a national database because you WILL get a match with high probability even if the perp is not in the database. DNA is not a unique identifier, at least no the way its used. In this case it sounds like they used it for verification, since the sought a comparison of a suspect with a specific baby's DNA. From a science perspective this seems quite reasonable. From a privacy PoV IDK.

dekhn 4y ago
In the way that it's used, DNA is as close to a unique identifier as you can get. There are many techniques. https://en.wikipedia.org/wiki/DNA_profiling https://en.wikipedia.org/wiki/DNA_profiling You can tune the stringency but they shouldn't be causing enough false positives that screening will just turn up random people. More likely to get close relatives of people in the room at some point. See "partial matching" on the linked page.

tablespoon 4y ago

> police attempt to match it with a fingerprint in their databases that you might have had to submit to get a drivers license Where is this required? Because I've never heard of such a thing in the US.

asdff 4y ago
They printed me in California at least.
hoistbypetard 4y ago
I've had licenses in NC, MA and VA. None of those required fingerprints.
s1artibartfast 4y ago
you need one on file for a drivers license in California. I didnt want to give it due to privacy, but well... I have to drive so here I am

impossiblefork 4y ago

It's very much logical reasoning, and it's not about DNA being scary. It's about a kind of perfidy. It's the reason you in war don't masquerade as someone who is wounded and to try to get at your enemy, and don't use fake medical stuff in ruses, &c (this of course happened once in Pakistan, but I count it as those responsible lacking in understanding and being short-sighted). You don't ever do anything that will in any way affect people's trust in the medical system, even indirectly. This has been understood for a long time, and is part of the reason why the Hippocratic oath (i.e. the actual Hippocratic oath) involves swearing to never do any harm.

tunesmith 4y ago

> the police attempt to match it with a DNA sample in their databases you might have submitted for a health screening. I know you were attempting to draw a parallel, but the difference is that the DMV is a government organization (part of the DOT), and your medical provider is not. There are different expectations of privacy. Which is close to the heart of the issue.

asdff 4y ago
Your medical provider provides plenty of information to the state at their behest as it is. Chances are that started with your birth when your birth certificate was made official. Sensitive medical information is not being used to solve crimes here, they aren't looking for people with certain conditions etc. They are asking if a sample matches another sample in a database and to what proportion they are in agreement. That's it.

salawat 4y ago

Law enforcement is using Third Party Doctrine and usage of non LE DNA databases to work around the requirement for probable cause. As I understand it, public health regulations are exacerbating the availability of this data by mandating submittal of DNA for screening, and retaining the data. There is also the CSI effect to take into account and once again, the bloody fact we don't need to be preserving this data in perpetuity. This is why Third Party Doctrine is a complete and total deconstruction of the 4th Amendment in practice.

asdff 4y ago
It would be a huge scientific loss to discard collected genetic material. We should be cataloging all DNA that we can, not just from humans but from crops we grow and ecological marker species that proxy ecosystem health. You never know if there will be some test uncovered in the future that you could use against these previously collected samples and make some life saving inferences. When you throw that data away, you've eliminated that possibility forever and damned future scientists.

criddell 4y ago

If you collect my DNA you're getting a whole lot more information about me than you would from a fingerprint. I guess it depends on how the DNA is stored. If it's an opaque hash, then I probably agree with you. I'd hate to become a suspect in a crime because of some profile worked up by a behavioral analyst at the FBI and something in my DNA suggests I could fit the profile.

asdff 4y ago
Well, that's not how its really used per say. They aren't looking for behavioral features, they are looking for pattern matches not unlike a fingerprint. The advantage of this versus a fingerprint is the heritability aspect. You share half your DNA with either parent and you can proportionally estimate degree of shared dna for relatives in a geneology. That means they don't have to make sure the killer is in the finger print database, a distant relative and some math can in practice expand your database.
- criddell 4y ago
  > They aren’t looking for behavioral features. I might be on board if you could make the stronger claim that they can’t look for behavioral features nor will they be able to in the future. A good hash provides that guarantee.
  - asdff 4y ago
    The argument is that they aren't considering phenotype information when they are solving crimes. How would that information even be used? A lawyer would have a stronger argument arguing a predisposition to criminality on environmental factors: a broken home, being raised when leaded gas was used, etc, versus arguing in terms of genetic association. These studies are not very robust connecting behavior and genetics because environment is a huge factor that explains the observed variances in these phenotypes. That being said, these data are being used for actually legally actionable things: first order pattern recognition using the same legal frameworks as fingerprints. Not second order "what do these patterns actually do in the body" or third order "what do these functions in the body do for the individual", each of which would probably take a PhD project to work out.

gopalv 4y ago

> 4th amendment violation because DNA is scary to the lay person it seems. There's probably a curve where it gets scary again as you know more about it. DNA isn't just identification. It is a lot more than just a unique identifier, it is a whole history and a lot of future probabilities. My list of SNPs is a lot less "if you have nothing to hide" about it. Imagine a government which looks at SCN1/SCN2 before issuing a drivers license.

pc86 4y ago
Is there a genetic component to being a skilled and/or safe driver? Society as a whole would probably be a lot better off if we stopped pretending driving around 4,000-lb hunks of metal at 80mph/130kph was some sort of inalienable right and actually showed some discretion in who was allowed to do it and who wasn't. But it's not realistic, especially if you live outside of a city.
asdff 4y ago
Well the government is not doing that in this case. They don't care about phenotypes for this analysis. The phenotypes are used for other analysis like public health efforts, but for law enforcement they just ask whether one pattern matches another and to what proportion it matches, and then if it matches a psuedorelative they go about to see if there is infact a person who could be this psuedorelative, then they go about and see if the person did commit the crime with other pieces of evidence.

crote 4y ago

There are two issues here. First, you constantly leave DNA everywhere. You are literally shedding it, even when you are not committing a crime. It is _guaranteed_ that DNA of innocent people ends up at crime scenes. While it is certainly useful at _confirming_ a suspect, it is way less powerful when trying to _find_ a suspect. Second, DNA matching is a matter of chance. While comparing a sample to a single potential match is extremely reliable, comparing a sample to a population is not. You're basically running into a birthday paradox here: given a large enough dataset, false matches are guaranteed to happen. If you use biometrics databases like this, you basically end up reverting the burden of proof: your DNA was at the crime scene, can you explain how it got there if you are indeed innocent?

asdff 4y ago
It's not exactly a birthday paradox because you have way more than 365 potential variants. Some 324 million. Plus its not discrete variants like having a single date of birth, you can have multiple combinations of variants. But broadly the big utility is in matching distant relatives versus strangers from the lot, and seeing if there is agreement with those putative matches with actual records and other hard evidence. You share half your DNA with either parent, 1/8 with your first cousin, and so on and so fourth for the rest of the human race. Using that information coupled with other pieces of evidence can yield a pretty reliable hit and is how they managed to catch the Golden State killer using DNA and genealogy.
xboxnolifes 4y ago
Does everything you just said not also apply to fingerprints? You leave them everywhere you touch, and people touch a lot of things. Maybe less so than DNA, since it's effectively a subset (things you touch likely have DNA from your hand skin, but things you don't touch might also have DNA from other things), but it's still just saying "you were likely here". And given a large enough population, wouldn't there also be many partial fingerprint matches? I'm not sure how these two things are issues when comparing fingerprinting to DNA matching. They seem to be applicable to both.

yetanotherloser 4y ago

Given the surprisingly poor perfection of dna "matching" and the tendency for public and law-court rhetoric to seriously misrepresent the odds of a mistake... at this point anyone who would voluntarily submit dna - or anything other than fight very hard against handing it over - has grotesquely poor judgement.

asdff 4y ago
Can you site a source documenting this poor perfection of DNA matching? I dug into this after reading your comment and I found the opposite was true, that a false positive as an odds on the rate of 1 in 1 billion. When you couple it with the fact you also need more than just DNA evidence to convict (which was done with the golden state killer, DNA was not the only source of evidence), the odds grow even smaller of 1) you having no alibi or potentially being at the place of the crime at the time and more evidence, and 2) you being that 1 in 1 billion match to the real killer. https://www.parliament.uk/documents/post/postpn258.pdf https://www.parliament.uk/documents/post/postpn258.pdf
- yetanotherloser 4y ago
  pop article and still too forgiving, but this is not a bad start: https://freakonomics.com/2008/08/are-the-fbis-probabilities-about-dna-matches-crazy/ https://freakonomics.com/2008/08/are-the-fbis-probabilities-... (it's still excessively charitable about the odds because the genetic factors are not really perfectly independent and even a tiny bit of interdependence wreaks havoc with large probability calculations) The link you cite with "1 in billions" odds is exactly the sort of misrepresentation I'm talking about. Combine smaller-than-pretended probabilities with big database trawling and it becomes a bit like the "birthday problem": it provides really good odds of finding someone to pin the crime on, but very little confidence that it was really them.
  - asdff 4y ago
    The birthday problem is different because there are 365 possibilities and every individual can only have 1 out of 365 states. For DNA there are over 300 million variants in the human genome and you can have different combinations of these variants. As far as matching 9 of 13 loci, thats not surprising to me nor concerning. If you left a sample at a crime scene it would match all 13 loci. Today the FBI uses at least 20 loci. On top of that, merely being a dna match does not mean you are going to jail. You need corroborating evidence just like how finger prints are used. The odds of a false positive that 1) is a dna match and 2) was in the right place at the right time and lacks and alibi and has a potential motive for the crime must be a trillion to one.