Oh, it’s not a good moral thing, it’s a bad skill thing. She just sees through me. Maybe she can tell when I worry about getting caught? Which is why I (always!) catch her off guard when I wander into total fabrication.
My late mother-in-law initially would swallow the most outrageous things that I told her. But after a few years Mom would pick up whatever clues I emote when I confabulate and she would put on her skeptic face when I waxed fantastical. Maybe it’s a mom thing?