The little big man (who, by the way, is no longer little) put a lock on his phone using his image. The way it goes is that the phone only opens if he puts his face in front of it and it detects that it is him trying to unlock it.
The little girl, naughty as she is, put her face in front of the phone.
And walah!!! It opened!!!
Now who still says they don't look alike?