Next time you’re about to toss a cigarette butt on the ground, consider this freaky fact: It takes less than a nanogram (or less than one billionth of the mass of a penny) of your dried saliva for scientists to construct a digital portrait that bears an uncanny resemblance to your very own face. For proof look to Hong Kong, where a recent ad campaign takes advantage of phenotyping, the prediction of physical appearance based on bits of DNA, to publicly shame people who have littered.

If you walk around the city, you’ll notice portraits of people who look both scarily realistic and yet totally fake. These techno-futuristic most-wanted signs are the work of ad agency Ogilvy for nonprofit Hong Kong Cleanup, which is attempting to curb Hong Kong’s trash problem with the threat of high-tech scarlet lettering. It's an awful lot like the Stranger Visions project from artist Heather Dewey-Hagborg, who used a similar technique a couple years back to construct sculptural faces as a way to provoke conversation around what we should be using these biological tools for.

In the case of Hong Kong's *Face Of Litter *campaign, the creative team teamed up with Parabon Nanolabs, a company out of Virginia that has developed a method to construct digital portraits from small traces of DNA. Parabon began developing this technology more than five years ago in tandem with the Department of Defense, mostly to use as a tool in criminal investigations.

Parabon’s technique draws on the growing wealth of information we have about the human genome. By analyzing saliva or blood, the company is able to make an educated prediction of what you might look like. Most forensic work uses DNA to create a fingerprint, or a series of data points that will give a two-dimensional look at an individual that can be matched to pre-existing DNA samples. “We’re interested in using DNA as a blueprint,” explains Steven Armentrout, founder of Parabon. “We read the genetic code.”

Ogilvy/Parabon

The DNA found on the Hong Kong trash is taken to a genotyping lab, where a massive data set on the litterbug is produced. This data, when processed with Parabon’s machine-learning algorithms, begins to form a rough snapshot of certain phenotypes, or traits. Parabon focuses on what it describes as highly heritable traits—or traits that have the least amount of environmental variability involved. Things like eye color, hair color, skin color, freckling, and face shape are far easier to determine than height, age, and even hair morphology (straight, wavy, or curly).

The Ogilvy team says it accounted for age by studying market research on the types of litter it processed. For example, people ages 18-34 are more likely to chew gum, so any gum samples were automatically given an average age in that range. Whereas the portraits of cigarette litterers, more common among the 45-plus group, were depicted as slightly older.

It’s an imperfect science in some regards, and yet, the capabilities are astounding—and more than a little scary. Ogilvy says it received permission from every person whose trash they picked up, so in that way, it’s not a true case of unsolicited public shaming. And Parabon itself says its services are only available for criminal investigations (and, apparently, ad campaigns). But the message is still chilling. A project like The Face of Litter should serve as a provocation to talk critically about privacy, consent, and ethics surrounding the unsanctioned appropriation of someone's DNA. So for now, the next time you drop that empty bag of Doritos onto the ground, you're in the clear. But in the future? Just know it's totally possible that you might be seeing your likeness plastered onto the subway walls.