So Your Second Cousin is a Criminal, and Other DNA Privacy Concerns

Legislation, Policies, Privacy

By: Kelly Bilz

Whether you’re a true crime enthusiast or a genealogy geek, you’ve probably heard about how DNA has been used to convict criminals for cold cases: a 1984 homicide case in Wisconsin, a 1967 murder (the oldest case when it was reported in May), and most famously, the Golden State Killer. (It bears repeating: the Golden State Killer!!!!!) These crimes were solved using the relatively new field of genetic (or forensic) genealogy, using DNA matches from direct-to-consumer (DTC) kits, like those from or 23 and Me, to narrow a list of suspects in a police investigation. Genetic testing kits go on sale around the holidays, so before you put one on your gift list, here’s the ways your DNA data could be used.

Genealogy–genetic or otherwise–is full of all kinds of unexpected discoveries, but normally, they’re the kind that happened upwards of 70 years ago. With genetic genealogy, if DNA matches that could share less than 1% of DNA (the amount shared by 3rd cousins is 0.78%), investigators can build family trees: one to find the common ancestor, and the other to work forward to the present day. You can see the process at work with renowned genetic genealogist, CeCe Moore, here.

Silhouette of two raised hands in handcuffs

But how much access does law enforcement legally have? This November, a warrant was issued in Florida for access to GEDmatch, a genealogy site, to search its database for DNA matches. This could pave the way for similar warrants to be made at other sites like 23andMe and GEDmatch has over a million users (who have not consented to the search), but that’s a small following compared to and 23andMe. This, naturally, has people concerned about the privacy of their data. 

Companies offering consumer genetic testing are trying to tighten up their privacy policies. Although it varies by state (and which site has been given a warrant), companies are lobbying to keep DNA data protected and to uphold the policy of their users through policy. They aren’t going down without a fight, which, if you’re one of the 26 million who have had their DNA tested, is a bit of relief.  

On the other hand, these privacy measures have drawn criticisms. Great, so no one knows you’re 80% Irish–and murderers just go free? In New York, in a story published just three days after the warrant in Florida, we hear another side of the story: a victim’s family whose state policies restrict this use of DNA evidence. In this case, bureaucracy and equipment seem to be the culprits, rather than privacy concerns, but these added restrictions do slow down investigations that, yes, could lead to the arrests of violent criminals. It’s a difficult balance between privacy and safety. 

judge’s gavel lying on top of platform

One thing that’s important to consider is the reach that DNA has: whether or not you’ve submitted a test yourself, your cousin might have. Your second cousin could have. Your third cousin, potentially, could have. And, especially if you’re of European descent, that makes you particularly easy to find. According to Kaiser Health News, the DNA from these websites will make 90% of Americans of European descent identifiable. Genetic genealogy is perhaps the only thing about our justice system that affects white people (well, more accurately, people of European descent) more than minoritized communities. (Maybe that’s why it’s being taken so seriously?) The point is, this isn’t data you can “opt out” of. If that relative you met once at a reunion ten years ago gets the genealogy bug, your DNA and your genealogical profile could become part of an investigation. 

You might also consider is that genetic genealogy can be wrong, mistaken, or misinterpreted. And if you are wrongfully convicted, depending on your state’s laws, further DNA testing might not save you anyway (which you can read more about on the Innocence Project website). Another factor to consider: DNA evidence is costly and time-consuming. Yet another factor: immense backlogs (like, most notoriously, the rape kit backlog). The thing is, a lot has been written about the “CSI Effect,” or expectations that courtroom cases must involve DNA evidence. Even John Mulaney jokes about running evidence through CODIS (and takes a dig at Dennis Fung from the O.J. Simpson trial–another landmark case regarding the use of DNA evidence). But DNA and consumer genetic testing kits aren’t only being used for criminal investigations (and, you know, the genealogical research that probably started it off). now offers an AncestryHealth kit, and consumer DNA testing kits are used for health-related purposes as well. As said previously, the sampling for these companies is predominantly from people with European ancestry, resulting in knowledge gaps for those not of European descent (mostly people of color). This lack of diversity can lead to inaccurate or misleading results, and for many consumers, the results can be difficult to understand, anyway. Another thing you have to look out for are fake DNA kits–as if you needed another scam to worry about, or needed more proof that people want your data. 

Advances in DNA and genetic genealogy can lead to breakthroughs in family trees as well as cold cases. Before you buy that DNA testing kit that’s been marked down for Christmas (or Father’s Day, or Mother’s Day), just make sure you think about the risks, too. 

Kelly Bilz

Kelly Bilz is a graduate student from Kentucky pursuing her MLIS with a specialization in academic libraries. She works in her university’s Special Collections as well as the local history department of a public library. Kelly first heard about intellectual freedom in her Information in Society course and has spent the time since arguing with her friends about intellectual freedom in algorithms, ethics, and institutional integrity. Because she is passionate about history and the cultural record, Kelly is interested in how intellectual freedom affects access to genealogical records and ethical collecting practices in archives. In her free time, Kelly enjoys listening to podcasts (especially Ear Hustle) and watching old movies (like Lady from Shanghai). Find her on LinkedIn.

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