...Ok not literally.

But 23 & me analyses your DNA and can tell you roughly where your genetics are from and in particular, could point towards a particular race of person.

We know that DNA testing is a common part of criminal investigations to match or rule out suspects, but if investigators were really at a loss, could they use the broad genetics of a suspect, say taken from the finger nails of a victim, to point towards a particluar race or someone of particular genetic origin?

I really don't mean this as a racial thing at all, just out of interest. If I, Scottish to the bone, committed a crime while on holiday in France, against someone that was a complete stranger to me and I them, would the police be able to say, well we know it's someone with Scottish origins?

I could see this being ethically questionable and possibly lead to a high frequency of false detentions. And on the basis of genetics / race makes it all the worse. Is this something that happens / could happen in the UK, US, Europe?


The legal situation is that these tests can give you a hint who the suspect might be, and in previous applications of the technique, existing voluntarily-provided genetic information from relatives sufficed to point to the actual suspect. You cannot arrest or convict based on a hint. A hint plus other facts can result in a warrant, which can result in a conviction. This is the case of the Golden State Killer. The details of the case are not generally known, but see this paper for a bit more information. Basically, they used public genetic databases to arrive at a tree of about 1,000 persons related to the suspect, and used other investigative techniques to narrow it down further. Here is the heavily redacted warrant affidavit that will give you some clue what else went into the search warrant leading to his arrest. Simply knowing "the suspect was of Northern European ancestory" is of insufficient specificity to support a search of all full-blooded and partial-blooded Scotsmen.

This "can" happen in the US, but the real question is, how effective is the technique. This is 99% a non-legal question about sufficiently extensive genetic databases. GEDMatch attempted to limit how their database could be used to catch criminals, but had mixed success. There have been attempts to limit police access to genetic databases at the state level, and no laws have been passed. The Dept. of Justice has limited restrictions on the use of forensic genetic data in cases that it is involved with in certain ways, see here. Basically, what they say is

A suspect shall not be arrested based solely on a genetic association generated by a GG service. If a suspect is identified after a genetic association has occurred, STR DNA typing must be performed, and the suspect’s STR DNA profile must be directly compared to the forensic profile previously uploaded to CODIS. This comparison is necessary to confirm that the forensic sample could have originated from the suspect

That paper which I mentioned above has detected in SCOTUS some retreat the position that there is no reasonable expectation of privacy in information willingly given to a third party, starting with US v. Jones, 565 U.S. 400. Conceivably, such testing could fall within the scope of 4th Amendment privacy constraints, given a suitable ruling (or argument that results in such ruling). At present, there is no legal impediment to that kind of testing.



The service used is called GEDmatch. There are Federal guidelines on how it can be used by law enforcement that receives Federal funding.

  • That is completely wrong: it is a DOJ policy that applies to DOJ investigations. Only Congress can set regulatory restrictions on recipients of federal funding. – user6726 Sep 12 '20 at 23:37

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