These possible factors behind the liar's behaviour can help make sense of what's happening, especially when there seems to be no other rational explanation. Jenny* shared a home with a young woman who would routinely and inexplicably tell lies. "I had a roommate who texted us that she had left the house when we were all pre-drinking at home. We looked through her curtains on our way to town and she was sat on her bed, staring at the wall," she says. "Another time she lied that she hadn't eaten our just-cooked lasagne despite it being just her and me in the house... She said her godfather was Alex James from Blur, and insisted she hadn't stolen my perfume (but started smelling just like it the day it went missing)."