Fred Benenson got an email from Facebook recently, informing him that it had detected his face in a number of photos and asking if he would like to be tagged in them. Facebook says DeepFace can determine if two photographs are of the same person 97.25 percent of the time, but there are still plenty of images that can trip up their most powerful machines, especially when it’s a family affair. If a person closely resembles one of their parents, a photo of the young mother or father could correlate and confuse the algorithm, says David Tunnell, the chief technology officer at NXT-ID, which specializes in three-dimensional facial recognition. In Facebooks case, confusing two family members was a bug, but one that points toward other potential uses for facial recognition, as the process also works in reverse.