Using ancestry DNA to solve crimes

A close up of a DNA lab, with a gloved hand placing down a cartridge

writer icon Lily Olsson     23ANDME   |   Tech Ethics     🕐 10. Oct. 2018

A serial killer was finally captured in California. Joseph James DeAngelo was revealed to be the Golden State Killer.

Infamous for committing multiple rapes in California from 1976-1986, DeAngelo was arrested in April 2018. He was found with the help of DNA. DNA that was previously donated to find out people’s ancestry, not criminals. Although it got a murderer off the streets, using DNA for purposes other than its original intent raises some very important questions on ethics and privacy.

Ancestry Sites Taking Off
Ancestry websites such as or were designed to help people navigate their past. focuses more on your family tree. 23andMe takes health into account as well, looking into the likelihood of certain diseases or traits that may be genetically linked.

Both websites do this by linking DNA to other contributors and sources to build a timeline of relatives all connected to you. Ancestry boasts over 10 million people who have been DNA tested while 23andMe has over 5 million users.

It is your DNA, and someone else’s too
Unless you are part of a set of identical siblings, your DNA is unique. DNA takes components from both the parent sources to create an entirely new strand. Because DNA always takes from the parent sources, it can be assumed that DNA has the potential to be traced back to the beginning.

Because of its continuous links to other sources, your unique DNA can still be linked to your siblings, parents, aunts, uncles, and much further back.

The Golden State Killer did not upload his DNA to one of the many ancestry websites. His relatives did. By narrowing down potential suspects from crime scene DNA, investigators were able to focus their attention on certain leads that led to his arrest.

Privacy in an Open Source World
Data is a powerful commodity in the online world. Many companies will go to great lengths to get their hands on user data. Ancestry websites are no different.

23andMe claims that it has never given user information to law enforcement.’s privacy statement says that it will only share information to comply with legal processes such as subpoenas or warrants., another genetic database, is what law enforcement used to track the Golden State Killer. GEDmatch’s terms of service indicate that user information will be shared with others.

Like many websites, however, the terms of service can be scrolled through quickly before accepting. There is no timer or monitored scrolling to prove that users read the terms of service.

DNA is considered one of the most accurate means of evidence when it comes to solving crimes. It can prove someone’s guilt or someone’s innocence. Now, it exists in databases, stored until it is needed again. If users knew that their DNA could be accessed so easily, would they still give it?

Ethics of DNA
In’s privacy statement, it says that they may share personal information in order to “protect the rights, property, or safety, of Ancestry, our employees or users.” It should perhaps be more clear whether the safety of the public overrides the personal rights of the individual.

The issue of safety can be difficult to define, as it can mean different things to different people. Presumably, an individual or group will make the call on whether public safety is at risk. With humans in charge, there may be cases of broad interpretations of safety. Such broad interpretations could potentially be used as a loophole for sharing information, under the guise of looking out for the general public safety. One has to ask if private websites will use this information without prejudice.

If someone does not consent to have their DNA taken, they still cannot stop their relatives from contributing their own DNA. This could draw a map right to them. Medical data is extremely private, should one's DNA be any different?

When the Golden State Killer was captured, many questions were raised. Although this case is worthy of celebration, perhaps people should also consider the repercussions this investigation may have on our private, personal futures.

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