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DNA Privacy and Law Enforcement: Should You Worry?

Have you heard that law enforcement has been catching criminals using genealogy combined with DNA? In this post, read more about DNA privacy and law enforcement.

Plus, find out whether you should be concerned, and how to protect your DNA privacy.

The buzz surrounding this issue began to grow once the public learned how they caught the infamous Golden State Killer using DNA and a few popular websites that people use to trace their ancestry.  Since then, discussions around DNA and law enforcement topics are rife with heated debates about privacy and ethics.

DNA Privacy and Law Enforcement_ Should You Worry_

Should you worry?

I have been hesitant to address this topic on my blog, primarily because there has already been a lot written about it on major publications.  I have received a lot of questions via e-mail, however, so I decided to weigh-in.

Below, I’ll tell you three reasons why I don’t think you should worry too much about the way that DNA information was used by law enforcement and professional genealogists in order to determine the identity of a dangerous criminal. This is why I still support DNA testing and the generous sharing nature of our online communities.

This opinions expressed in this post are mine, and mine alone. It’s important for every DNA tester to understand how their data is being used and to make their own decisions about privacy.

Important details about law enforcement catching criminals with DNA

Before I go further into this topic, some background is appropriate.  Just to make sure that we are all on the same page working with the same facts.

DNA testing companies don’t share DNA data with law enforcement without a warrant

No major DNA testing company gives any special information to any law enforcement agency about any DNA testers or website users without a warrant. This means that law enforcement must have a warrant to access information that is not available to the average user of any given website.

In addition, some DNA testing companies do not allow DNA uploads to their site. By default, this prohibits the use of their database by law enforcement in the manner described in this post.

This means that when you test your DNA or upload it to a DNA testing site to find DNA matches, you aren’t just “giving” your DNA to law enforcement.

Law enforcement uses the same techniques that we use to build our family tree using DNA matches

Law enforcement used common genetic genealogy strategies and DNA data obtained from a sample of DNA taken from a crime scene where the Golden State Killer had allegedly been in order to determine his identity

The DNA data from the Golden State Killer was uploaded to Gedmatch, a popular website used by professional and amateur genetic genealogists.  Law enforcement officials were able to see genetic matches to the killer, as well as some family tree information on some DNA matches.

The criminals that they catch using DNA techniques are really, really bad

Most of the resources dedicated to catching criminals using genetic genealogy techniques are focused on finding dangerous criminals. We are talking about people who have committed violent crimes, like rapes and murders.

Sometimes, these criminals have committed multiple rapes and murders!

The Golden State Killer, also known as his real name, Joseph James DeAngelo, was arrested after allegedly committing at least 13 murders, at least 50 rapes, and at least 100 burglaries.  The general consensus is that it’s a good thing that this guy is off the streets.

I mean, it’s like a really, really good thing.

So, without further ado, please read the top three reasons that you shouldn’t worry too much about law enforcement and DNA privacy.

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#1  Police don’t need your actual DNA to use DNA databases to find criminals

As I mentioned in previously, the police were able to upload DNA information obtained from a DNA sample taken from a crime scene to the Gedmatch website.  The way the detectives, or a genealogist assisting the detectives, used the website is exactly how you and I would use it. 

We’d upload our data, wait for it to process, and then perform a One-to-Many comparison to find all of our DNA matches on the site.

The results would look something like this:

what kind of information would be available to law enforcement on gedmatch

That’s it.  It’s just a list with some weird looking details on it.  From the image above, you can see that someone could learn a few things about the criminal’s DNA matches (i.e. me and you, the average “Joes” on the site):

  • where someone did their initial DNA test (“A” is for Ancestry in the kit number, for example). 
  • whether the match is male or female, and see how much total DNA shared
  • the length of the largest DNA segment shared, as well as their name (or their designated alias)
  • the e-mail address that they used to set up their account.

Genetic genealogists use DNA information to build family trees to locate criminals

If I were the criminal, and law enforcement had uploaded a file with my DNA information in it, there are some things that they could do to try to figure out who I am. First, they’d have to hire an expert in genetic genealogy.

Someone who is very skilled at genetic genealogy, which is the art of using DNA and genealogy to build a family tree, could use the above information to put together a basic family tree for me. This is especially true if they have a subscription to Ancestry or another site for searching records, which I imagine might be true for law enforcement officers. 

And if we are honest, if they are working with law enforcement, they might have access to some high-quality databases with information on living people, which is something most of us genealogists have trouble locating.

How would they build a tree?  Let’s use my cousin, Shelley, as an example. She’s on my list in the image above, and we can see how much DNA we share.

We share 134 cMs, which means that we are somewhere between second a third cousins, most likely.  With that knowledge, they research Shelley’s family tree, which can be easily located on her Ancestry profile.

Second cousins share great-grandparents and third cousins share great-great grandparents.  The genealogist working on behalf of law enforcement can then build a family tree using another DNA match (my cousin Bo), and then see where the trees overlap – BINGO.  They’ll have found the people from whom I directly descend. 

If they want to get really fancy, they could build a few more trees Jane and John’s trees (and their knowledge of how closely we are related).

If I had committed a crime, then they could make a list of all of the people who descend from the ancestor that they identified, which would be a pretty short list.  Then, they could eliminate my other family members based on geography, age, sex, and other factors. 

It’s likely that law enforcement dedicated enough to hire a genealogist has been motivated to find the criminal (i.e. me) for quite some time. They might have a long list of suspects and clues about who they believe might have committed this crime.

They could then compare existing clues to narrow it down to one or two people. If one of them is me, they’ve got me.

Phew – it’s a good thing I try to keep my nose out of trouble!

#2  Law enforcement can learn about you or your relatives without your DNA

Even if you decided that you don’t want your DNA to be in any database, it doesn’t matter.  Your identity, and the identity of any of your biological relatives can be found with varying degrees of effort by using the DNA of your distant relatives.


Because your DNA doesn’t only belong to you.  Your DNA is made of up tiny pieces of DNA called “DNA segments” that you inherited from thousands of ancestors. 

All of those ancestors had other descendants and many of those descendants carry little pieces of DNA that they share in common with you.  To simplify this complicated topic, you can imagine that that you could basically assembly your entire genome (or at least most of it!) using DNA segments from all of your living close and distant relatives.

This means that even if you don’t do a DNA test, your sibling, parent, child, nephew, cousin, or aunt might decide to do so. 

All of these relatives share a significant percentage of DNA with us, and their DNA information is enough to assist law enforcement in tracking down a criminal third cousin twice-removed or those volunteers searching for the identity of a Jane Doe in their process. 

Even distant cousins can share large segments of DNA with us, and if you have enough distant cousins out there who have tested, a dedicated, knowledgeable professional could learn much more about us than we could imagine.

For me, the benefit of having my DNA in the database and being able to learn about my ancestors, build my family tree, and help my adopted cousins far exceeds my concern – especially considering that more than two dozen of my close and known extended family members have also done DNA tests. 

If a member of my extended family decided to commit a terrible crime and law enforcement decided to use DNA, there is plenty of DNA information about my family floating around out there.  I won’t be able to stop anything by abandoning my hobby.

As I remember reading on a blog comment a few months ago: “The toothpaste is out of the tube”.  Might as well use it.

Just saying!

#3  The “greater good” can outweigh individual DNA privacy concerns

I’m sure we can all agree that it is a good thing that heinous criminals are caught.  While I can’t speak for the family and close friends of the victims, I would be surprised to hear that any of them take issue with the methods used in the investigation. 

People who uploaded their DNA to Gedmatch knew, or should know, that their information is going to be used by distant family members or even professional genealogists in order to build family trees.  Law enforcement basically built a family tree for the killer using the same information that you and I could obtain from uploading our DNA to the site.

Law enforcement has used techniques similar to what I have described in order to catch dozens of criminals. This means that lots of dangerous people are off the streets and that our families are just a little bit safer.

There are even volunteer groups who dedicate their time to help law enforcement identify the names of John and Jane Does, bringing closure to many families.

We exchange privacy for security all the time – DNA is no different

I believe that there are times when it is appropriate to make small privacy concessions in order to live in a safer society.  We do this all the time in other aspects of our lives. 

For example, in order to have the freedom to drive a vehicle, we are required to register as a driver in a government database.  The idea is that it is safer to have licensed drivers instead of unlicensed drivers. 

Some states even fingerprint people for a driver’s license, and all states collect personal information on their drivers.

Additional examples of privacy concessions in exchange for safety:

  • We allow ourselves to be intimately searched in order to board an airplane
  • When we go to a doctor, we tell them just about everything they ask about ourselves and our families in order to receive accurate and thorough medical care
  • If we want to keep our money in a bank, we have to provide a significant number of personal details to the bank, which they could share with the government in order to identify us as criminals should we exhibit suspicious banking behavior

How to protect your DNA information from law enforcement and others

We leave traces of our lives all over the internet, but it is especially important to be aware of the type of details we reveal on the internet about our DNA.  This is precisely because our DNA doesn’t belong to just us – our entire family depends on us to use our DNA wisely (whether they know it or not!). 

While I don’t think we should stress out about DNA privacy, or stop doing genetic genealogy altogether, I do feel like it is smart to take some precautions.

Below are some ideas on how to control the information that can be found about you on genealogy websites:

  • Create a designated e-mail address using an alias that you use to correspond with your DNA matches, and use this e-mail for every DNA website that you use
  • Make sure that you don’t post information about living family members on family tree websites
  • If you are especially concerned with privacy, make sure that all of your family tree information is set to private (not publicly viewable)

Check each DNA site carefully for privacy settings and policies

You should also carefully research each site that you would like to use, especially if it requires you to upload your DNA.  If they don’t tell you what they plan to do with your DNA, consider asking them. 

If website doesn’t provide a helpful answer, weigh the risk of using their service against the potential reward that you might gain from the information you could learn from their service. At the end of the day, it’s up to you.

Don’t share your Gedmatch kit # on public forums

Don’t post information like your Gedmatch kit # on public forums, Facebook groups, or other social media platforms.  If you would like to share this information, make sure to send it in a private message or an e-mail.

Google yourself to see what information is available about you

Remember that someone who is interested in learning about you (most like an adopted family member or someone trying to figure out how you might be related) will use Google to see what they can learn about you.  Most people are very innocent in their intentions and just want to determine your connection with them. 

Keeping this in mind, Google yourself to see if you are comfortable with the information that is out there, and adjust your privacy settings as necessary.


I hope that this post helped shed some light on how DNA information can be used by law enforcement. Plus, I hope it helped you decide whether you are comfortable to be with your DNA information being used in this manner.

I know that many of my readers will have strong views on this topic, and I would encourage you to share them in the discussion below.  I hope to keep the discussion friendly, however, since we will all learn better by keeping it civil. 

Of course, if you have any questions, I would love to hear from you!

Thanks for stopping by today!

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