Science & Technology

You Might Be Surprised How Much DNA Can Reveal About You

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We told you once about the CSI effect: the purported phenomenon where the technology that TV detectives use to solve their crimes tends to make regular people think DNA evidence is magic rather than a technique with plenty of limitations and difficulties. In truth, the CSI effect is likely not as bad as courtrooms say. And thanks to new developments in technology — and new laws that empower that technology — DNA evidence is now capable of revealing more than you ever thought possible. Your appearance is just the beginning.

A Genetic Mugshot

It's probably not news to you that the color of your eyes, hair, and skin are all encoded in your DNA. But isn't it interesting how they don't ever really use that data on cop shows? Instead, the way most forensic scientists mainly use genetic material, both on TV and in real life, is to compare a found DNA sample to the DNA of a suspect. Really, it's good for one thing: proving if this specific genetic material belongs to this specific individual. That's a valuable tool, but it doesn't do much to help detectives strategize their search for suspects.

Now, thanks to a new law, German police in Bavaria will be able to use DNA evidence not only to match it with an existing suspect, but also to come up with a general physical description of an unidentified suspect. That means being able to positively say that a suspect has a certain hair color, eye color, and skin color.

As you might imagine, the practice isn't without its controversies. The law was passed in response to the arrest of an Afghani asylum seeker —an arrest which, some people claimed, could have happened sooner had the police been empowered to derive a physical description of the suspect. It's too easy to imagine that DNA evidence pointing to a person of color would result in marginalized communities being even more unevenly policed.

The DNA Methylations of Our Lives

The fact that some police departments are using DNA evidence to paint a picture of their suspect is eyebrow-raising, but at least it's in the realm of things we knew you could do with DNA. But thanks to a phenomenon called DNA methylation, those same departments (actually, many more) could soon roughly pinpoint the age of their suspects as well. Methylation is the process by which methyl molecules attach themselves to DNA strands, which leaves the gene sequence intact but prevents certain genes from being expressed. As a person gets older, their DNA is methylated in predictable ways, making it possible to guess at their age. Since this test doesn't look at actual DNA sequences, it's not subject to some of the more common privacy laws — and according to some researchers, that's a big problem for medical security.

That's because DNA methylation can reveal more than just the age of the person. It can also reveal medically confidential information such as whether or not they have cancer or other potentially dangerous conditions. As paper co-author Bram Bekaert told Science magazine, it's not even just the suspect's privacy that you have to worry about.

"DNA methylation is in part heritable," he says. "It's not just about the privacy of the individual himself ... It's also about his son, his daughter, or his parents or his siblings." They suggest a couple of solutions, as well, and they're pretty common sense. You could restrict the markers that a forensic scientist is allowed to examine, although that could negatively impact the accuracy of the age prediction. Or, you could simply restrict the data that the scientists are allowed to convey to other authorities, thus keeping the person's medical privacy intact.

Want to get inside the mind of a forensic investigator? Pick up Steve Jackson's "No Stone Unturned" to dive into NecroSearch, one of today's largest and most effective international forensics networks. The audiobook is free with your trial membership to Audible. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

Forensics on Trial

Written by Reuben Westmaas July 17, 2018

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