In addition, fingerprints and faces are particularly bad biometrics for keeping secrets, because attackers can get hold of them without you noticing. E.g. anyo

In addition, fingerprints and faces are particularly bad biometrics for keeping secrets, because attackers can get hold of them without you noticing. E.g. anyone can take a picture of you in a crowd, or lift your fingerprints if they can get to somewhere you've been. But they can't do a surreptitious retinal scan on you.