Wherever we go, it gives us away. Until now, only criminals have bothered to erase their DNA from crime scenes. In the future, should we be wary of increasingly advanced forensic science? Although we’re still a long way from reconstructing someone’s face with their DNA, the research has made significant progress in recent years.

Phenotyping and DNA

Coding our physical traits is one of DNA’s fantastic biological tools – it’s the reason monozygotic twins are perfectly identical. For several years now, DNA has allowed us to identify certain physical traits of an individual: their eyes, their skin, their hair. But other characteristics, called polygenic – that is, involving several genes – have proved more difficult to determine. As machine learning gets more and more sophisticated and while the databases grow, genetic prediction is making significant progress. In 2017, a study by the American institute Human Longevity declared that “by combining new bioinformatic methods and artificial intelligence,” reconstructing a person’s exact face using only their DNA is possible.

To do it, scientists sequenced the genomes of more than 1,000 people of varying ages, genders, and ethnicities, which they then scanned into 3D. An artificial intelligence combining DNA and scans were able to match genetic markers to facial structures and to determine the thickness of lips, bone structure, forehead prominence, and even the size of the nose. The algorithm then evaluated age, body mass index (BMI), eye color and hair color. These characteristics, once established, helped it guess ancestral origin and sex. In the end, Human Longevity’s AI managed to identify a person from their genetic data  in 75% of cases.

However, although the advances are real and some of its results astounding, the subject polarizes researchers, and the study was received with a shower of critique. The genetics community generally believes it’s impossible for us to determine a person’s individual traits in an accurate manner: to them, this kind of analysis relies on data averages, evaluated by age and ancestral origin of the subject.

A new weapon for investigators?

Reconstructing a face from DNA may be one of the police’s wildest dreams. And it’s not entirely science fiction. Investigators have sent out calls to businesses offering this kind of service, capable of creating at least a robotic portrait, the New York Times reports. That’s what the company Parabon claims: to be able to precisely determine the physical appearance of a person using their DNA, based on a predictive model consisting of applying machine learning to a genetic reference database. With it, one can identify skin color, eyes, hair, freckles, ancestral origin and face shape. A “forensic artist” then creates the reconstruction on a computer.

Inevitably, this kind of methodology has inspired skepticism, especially in the judicial sector where any error can have dramatic consequences on individuals’ lives. Still, when cross-checked with other sources of information, the tool can be extremely useful – not so much to predict as to absolve subjects. More trivially, the tool can also be applied to archeology. That’s how the UK put a face to Cheddar Man, the oldest complete human skeleton in the country, and in February we learned, via The Guardian, that his skin was brown and his eyes blue.

A privacy issue?

In order to determine faces in reliably, we’ll need to develop a much more precise biometric database. In addition, countries’ genetic databases are largely Euro-centric, which creates a problematic risk when the subject being “predicted” comes from any other part of the world. Still, some of the results of these techniques are already shocking. The fascinating progress presents certain questions: so far, Parabon declines to use its tools in lieu of facial recognition systems. Will it always?

Amazon is already selling facial recognition systems to American police units, reported The Verge on May 22. The two fields are inevitably threatening to unite. A lot of genetic data has already been published, especially by researchers. Governments including China, India with its Aadhar system, and Australia with its gigantic database The Capability, are using increasingly sophisticated facial recognition and biometric technologies. As the degree of precision refines, the ability to identify people will be more and more accurate, and we don’t know what the owners of these systems will do with it.

Therein lie the privacy issues: our DNA contains personal information, which would require new means of protection. Will we need to encode our DNA in the same way that we encode our conversations, in order to protect them from intrusions, as Wired suggests?