DNA litterbugs

Many of you will have already seen the image above, as it's been all over the papers and filling up my feed on social media. For those of you who haven't heard, a campaign has been launched in the city of Hong Kong called 'The Face of Litter' which aims to shame people who have left litter on the streets. The campaign team collects litter with traces of human DNA, such as chewing gum and cigarette butts, and uses the genetic material to create an image of the litterbug's face.

The Chief Creative Officer at Ogilvy & Mather (the company that came up with the idea) said to the Daily Mail:

'Litter is such a major problem in Hong Kong and thanks to newly available DNA technology we can now put a face to this anonymous crime and get people to think twice about littering.'

Now, many of my friends have been asking me whether it is actually possible to re-create someone’s exact face just from a DNA sample. Of course, the answer is no! Although genetic material obviously makes a significant contribution to what people’s faces look like, there are so many other factors that cannot be accounted for from looking at DNA alone. A human’s environment (both pre-and post- natal) also has a big effect on what their face and body looks like. People can have scars on their faces from injuries, or broken noses or cheek bones, and can even have nerve damage from past illnesses or accidents which can completely change the shape of their faces. It’s also worth pointing out that some people have plastic surgery, so their DNA will definitely not be indicative of their face.

What I think needs to be explained more thoroughly to the general public is that your DNA does not define absolutely everything about you, just because you have a certain genotype does not mean that you will exhibit the associated phenotype (I talked about gene expressivity and penetrance in a previous blog post). Just because you have a certain gene in your DNA doesn’t mean that it is expressed, studies have shown that gene expression can be affected by a multitude of social and environmental factors, including exposure to chemicals, UV light, diet and more physiological issues such as trauma or abuse. It is generally accepted in the scientific community that nature and nurture work in tandem to create people and personalities, but the general public seem to stick to the more rudimentary view that everything about you is defined by your genes- and this is re-enforced by the way the media talks about genetics-related issues.

So to begin with, I was very sceptical about the accuracy of the ‘Faces of Litter’ that were being posted all over my news feed- as there was no evidence in the papers that the campaign had taken environmental factors into account. After looking further into the campaign, it became clear that they had. They did not just look at the DNA from the litter, they combined it with other demographic data to produce a more accurate approximation of the culprit’s face- the same as they use in forensics to predict what criminals faces might look like (the process is called DNA Phenotyping).

The campaign also conducted market research on the types of litter that are found. For example, in Hong Kong, more people chew gum between the ages of 18 and 34, and smoking is more common after the age of 45. They used information like this to guess the age of the culprits more accurately.

This is by no means perfect science, and the resulting images may not actually bear very much resemblance to the people they’re trying to shame. Ogilvy & Mather are happy to admit this, stating:

“While this method may not identify specific individuals, it will be enough to make people think twice about littering. The campaign combines a public service message with science and technology, enabling us to communicate with Hongkongers in a very different way.”

Unfortunately, the papers are singing a different tune, most claiming that the campaign is able to create a very realistic image of a litterbug from their DNA alone.

So the main points you can take away from this blog post is that you cannot create an exact image of someone’s face from their DNA, and you can’t trust everything you read in the media about science, as they often get it wrong! But assuming that the all papers are wrong without going back and looking at the evidence yourself is slightly jumping the gun!