Apple XR Face ID unlocks for my sister and I. We are not twins nor we are alike.
My iphone Face ID unlocks phone for my sister everytime she tries even though we look very different.
iPhone XR
Question marked as
If your sister ever tried to open the phone with her face and failed, but you followed by entering your passcode to open it, you essentially thought Face ID to also accept aspects of her face. This doesn’t often allow two separate users, but is how Face ID learns to recognize people even when their appearance changes (growing a beard, for example).
Reset Face ID and teach it to recognize your face anew and do not “confirm” your sister’s face by entering the passcode after she tries to open it with her face.