4 ms·

Lots of scandals around DNA evidence as well. It’s not the science itself that’s wrong, but mistakes can be made and were made during collection and in interpre

Lots of scandals around DNA evidence as well. It’s not the science itself that’s wrong, but mistakes can be made and were made during collection and in interpretation.

amenghra 4y ago
There’s also cases of people who received a transplant who then supposedly have two (or more) different DNAs in their blood.
- throwaway894345 4y ago
  Wow, that's pretty crazy. I never really thought about how transplants imply two different sets of DNA cohabitating in the same body.
  - neaden 4y ago
    I think the relevant transplant is bone marrow, since that produces Red Blood Cells. Here is an article about it:https://www.nytimes.com/2019/12/07/us/dna-bone-marrow-transplant-crime-lab.html https://www.nytimes.com/2019/12/07/us/dna-bone-marrow-transp...
  - wahern 4y ago
    Pregnancy presents a similar situation, and fetal microchimerism among parous women is not uncommon. This also includes, supposedly, brain tissue: https://www.science.org/content/article/bearing-sons-can-alter-your-mind https://www.science.org/content/article/bearing-sons-can-alt...
  - jacobkg 4y ago
    A founder I worked with had both a bone marrow transplant and a lung transplant. He named his company 3dna to commemorate having three sets of DNA in his body
- kstrauser 4y ago
  It also turns out that chimerism may be a lot more common than we’d thought.
knodi123 4y ago
Wasn't there a famous incident where the police assumed they were dealing with a serial killer because identical DNA was found at dozens of crime scenes, and only much much later did they learn it was the DNA of a guy who worked at the DNA analysis lab who didn't always wear gloves like he was supposed to?
- nebalee 4y ago
  Sounds similar to this: https://en.wikipedia.org/wiki/Phantom_of_Heilbronn https://en.wikipedia.org/wiki/Phantom_of_Heilbronn
  - knodi123 4y ago
    No, it was exactly that, and I misremembered some details. :-P
LtWorf 4y ago
Nowadays DNA is matched by a proprietary software that nobody knows if it's buggy or not. But I've never seen a non buggy software before…
tsimionescu 4y ago
There is some amount of the science itself being inconclusive, as no one has really studied things like "how likely is it for DNA that matches X's to n% precision to be in a location Y given that X has/has not visited that location". Even discounting intentional placement of evidence, we really don't know how likely it is to find pieces of your DNA in places near to those you frequent - say, in the lobby or elevator or first floor of an apartment building you pass by every day, but have never entered. This is especially important given partial matches, since it's likely thousands of people pass by a building each day that have never made it inside - so the chances of an accidental match increase greatly (while also being guaranteed to match corroborating evidence, such as security cameras seeing you next to that building on the day of). Conversely, we also don't know how likely it is that you can avoid leaving your DNA in a place you have visited to commit a crime. Now sure, there are cases like "we found a large smear of blood, all of it containing DNA that matches this suspect 99%, and the suspect has an obvious open wound/scab"; or, the same smear containing DNA that only weakly matches the suspect or the victim or any known eye witness, which is extremly good evidence that someone else was at the scene. But when one hair or bit of spit is found in an apartment that matches someone who does live around that area, we don't really know if that means anything.

Lots of scandals around DNA evidence as well. It’s not the science itself that’s wrong, but mistakes can be made and were made during collection and in interpretation.

amenghra 4y ago

There’s also cases of people who received a transplant who then supposedly have two (or more) different DNAs in their blood.

throwaway894345 4y ago
Wow, that's pretty crazy. I never really thought about how transplants imply two different sets of DNA cohabitating in the same body.
- neaden 4y ago
  I think the relevant transplant is bone marrow, since that produces Red Blood Cells. Here is an article about it:https://www.nytimes.com/2019/12/07/us/dna-bone-marrow-transplant-crime-lab.html https://www.nytimes.com/2019/12/07/us/dna-bone-marrow-transp...
- wahern 4y ago
  Pregnancy presents a similar situation, and fetal microchimerism among parous women is not uncommon. This also includes, supposedly, brain tissue: https://www.science.org/content/article/bearing-sons-can-alter-your-mind https://www.science.org/content/article/bearing-sons-can-alt...
- jacobkg 4y ago
  A founder I worked with had both a bone marrow transplant and a lung transplant. He named his company 3dna to commemorate having three sets of DNA in his body
kstrauser 4y ago
It also turns out that chimerism may be a lot more common than we’d thought.

knodi123 4y ago

Wasn't there a famous incident where the police assumed they were dealing with a serial killer because identical DNA was found at dozens of crime scenes, and only much much later did they learn it was the DNA of a guy who worked at the DNA analysis lab who didn't always wear gloves like he was supposed to?

nebalee 4y ago
Sounds similar to this: https://en.wikipedia.org/wiki/Phantom_of_Heilbronn https://en.wikipedia.org/wiki/Phantom_of_Heilbronn
- knodi123 4y ago
  No, it was exactly that, and I misremembered some details. :-P

LtWorf 4y ago

Nowadays DNA is matched by a proprietary software that nobody knows if it's buggy or not. But I've never seen a non buggy software before…

tsimionescu 4y ago

There is some amount of the science itself being inconclusive, as no one has really studied things like "how likely is it for DNA that matches X's to n% precision to be in a location Y given that X has/has not visited that location". Even discounting intentional placement of evidence, we really don't know how likely it is to find pieces of your DNA in places near to those you frequent - say, in the lobby or elevator or first floor of an apartment building you pass by every day, but have never entered. This is especially important given partial matches, since it's likely thousands of people pass by a building each day that have never made it inside - so the chances of an accidental match increase greatly (while also being guaranteed to match corroborating evidence, such as security cameras seeing you next to that building on the day of). Conversely, we also don't know how likely it is that you can avoid leaving your DNA in a place you have visited to commit a crime. Now sure, there are cases like "we found a large smear of blood, all of it containing DNA that matches this suspect 99%, and the suspect has an obvious open wound/scab"; or, the same smear containing DNA that only weakly matches the suspect or the victim or any known eye witness, which is extremly good evidence that someone else was at the scene. But when one hair or bit of spit is found in an apartment that matches someone who does live around that area, we don't really know if that means anything.