I suppose in reality it’s the average of people who post pictures online and are willing to display it publicly, and probably weighted slightly by how many pictures of a person are uploaded (e.g. if someone has uploaded tens of thousands of pics of themselves - a celebrity or whatever - they will throw the average slightly towards their own face). Assuming the sample set is something like: all of social media photos of a person’s face.
I suppose in reality it’s the average of people who post pictures online and are willing to display it publicly, and probably weighted slightly by how many pictures of a person are uploaded (e.g. if someone has uploaded tens of thousands of pics of themselves - a celebrity or whatever - they will throw the average slightly towards their own face). Assuming the sample set is something like: all of social media photos of a person’s face.