Law enforcement arrested someone they’ve been after for 40 years this week–all because of a genealogy site.

Joseph James DeAngelo, 72, was identified as the “East Area Rapist” after DNA collected from a crime scene years ago was matched to DNA submitted to a family tree site by a relative of DeAngelo. The elderly man is allegedly responsible for almost “50 extremely sadistic rapes and 12 murders” during the 1970s and 80s.

If DeAngelo is guilty and removed from society (or better yet, removed from the entire earth), that’s a great thing. The question, however, is how that was done, and what implications there are for those who are caught up in investigations even if they’re innocent, simply because someone in their family put DNA into the “system.” Bottom line: if someone in your immediate/extended/distant family submits DNA to a genealogy site, some of yours gets submitted too.

The DNA Market

Family research and genealogy is a big hobby–and a big industry. The average yearly membership for sites like Ancestry.com and MyHeritage.com is well over $120, and the more databases and information you want access to, the more you pay.

DNA analysis is all the rage now as well. Companies like 23andMe offer to tell you where you come from, and the commercials always show some interesting revelation as a result. The person in the ads always finds out they had proud warriors in their lineage, or some kind of royalty. Some people are even shown to have ethnicity they never expected; a long-lost relative from a completely different country or a forbidden affair and resulting love child. No one in the commercials is ever told that the last 400 years of their ancestry was made up of dirt farmers. That just wouldn’t sell DNA kits.

At any rate, folks line up to buy the kits, which consist of a tube you spit into and send off to the lab. No one ever really thinks about the fact that you no longer own that sample–and it contains biological information that identifies you. Think about that–you no longer control a piece of biological information about yourself, that can now be manipulated and used for whatever purpose the holder deems.

“Oh,” you’ll protest. “Those companies destroy the sample after they analyze it.” Sure. Where’s the analysis? They don’t need the sample once that’s done. They can tell you no one else will ever get their hands on the sample–and be completely truthful. Do they send the report around, however? That’s the real question.

Using the Reports

A sadistic criminal allegedly left his DNA at a crime scene many years ago. All the law enforcement work in the world couldn’t catch him, and during the 1970s and 1980s, the East Area Rapist wreaked havoc on California communities in the Sacramento area.

The break in the case came after a cold case squad started matching DNA from those crime scenes to online family trees that had members who had submitted DNA.  You see, you can access DNA profiles from other people. MyHeritage.com, for instance, lets you access the DNA for your family members; if you upload DNA data of your own, the site will match you to people with similar profiles.

I’m sure you can see how this could play out. Detectives could create a profile with their collected DNA from the crime scene, and use it to springboard into the correct family groups, and from there whittle it down to the right person while matching results with known geographical data such as residence locations at the time of the crimes, etc.

They arrested DeAngelo this week after using DNA databases from family tree sites to do just that.

What Are the Implications?

What makes DeAngelo’s case worrisome isn’t that a potential rapist and murderer is off the street. In fact, there’s a reason why his particular case is getting so much attention. It’s not the first case that used DNA from genealogy sites, but it’s one of the first to get national media coverage. The reason is normalization. People are far more apt to shrug off a privacy or rights violation if it’s done to get a monster out of society.

Let’s change a few details. What if someone was arrested because some touch DNA was found on ‘subversive’ pamphlets and police found related profiles on a family tree site? Is it still okay to do then? What if DNA from a genealogy site was used to identify someone who was working in an underground network that provided magazines and ammunition to states where it was banned? What about then?

It’s easy to look at DeAngelo, hear the details of his alleged crimes, and cheer that such out of the box methods were used to finally catch him. That’s why his case is being used as the example; you’ll always see these methods hailed as helping to catch the monsters.

Those methods, however, are never just used against monsters–and if the government is deciding who the monsters are, you have an even bigger problem.

The best part is that DNA related to you may already be on file from a family member; you may never even know.