If I recall correctly, on the DS Lite or DSi there was a feature where the camera would take a picture of two separate faces and display a percentage similarity between them - it may also have outputted a possible relationship for the two people, e.g. daughter, mother etc. This was not related to face recognition, it was just an added feature on the console. However, I cannot find mention of this anywhere on the Internet, which leads me to wonder if it was not in fact an inbuilt DS feature but part of an actual game.
Did this feature ever exist or is my memory incorrect and is there a way to access this feature on the 3DS, or was it not transferred?