Biometrics have been around for a little while. I first encountered them in a Mission Impossible movie, where they have to break into a secure room that requires a fingerprint, an iris scan, and facial recognition (I think). For me, at the time, it was firmly in the realm of sci-fi. The technology caught up pretty fast after that, if it wasn't already in play and I just didn't know about it, and then I saw fingerprint and then facial recognition hitting smartphones. It turned out to be a little klunky but as time has rolled on it's effective enough. The main caveats against it are:
1) Anyone ranging from commercial third-parties to governments can build or buy these databases to scan for their own purposes. Most recently this has happened with the genetic data from heritage websites
2) These can be easily spoofed. There are anything from 3D printed fingerprints to holographically projected faces which can break the biometric authentication methods of devices.
Something interesting that popped up at the tail end of the biometric development history is gait technology. I think I read something like >80% accuracy, something like 86%, based off of how a person walks / comports themselves. I can't remember if this has been spoofed yet or not but since it requires whole body movement it seems at least harder to pull off, for those situations where the threshold it has is sufficient.
The most recent development in this field is a Pentagon developed laser that can identify people by their heartbeat. It requires that a person sit or stand still for 30 seconds to be accurate but it's over 90% accurate and, so far but we'll have to wait until people actually get their hands on the tech, seems much more difficult to spoof than other biometric methods.