It takes a feast of facial imagery to teach a machine how to recognize an individual person.
This is why computer scientists so often use the faces of Hollywood celebrities in their research. Tom Hanks, for example, is in so many publicly available photographs that it’s fairly easy to build a Hanks database for algorithm-training purposes.
Depending on a researcher’s needs, there are many other available databases of human faces—some featuring tens of thousands of images. These collections of faces draw from public records like mugshots, surveillance footage, news photos, Google images and university studies.
It’s entirely possible your face is in one of these databases. There’s no way to say for certain it isn’t.
Your face is yours. It is a defining feature of your identity. But it’s also just another datapoint waiting to be collected. At a time when cameras are ubiquitous and individual data collection is baked into nearly every transaction a person can make, faces are increasingly up for grabs.