I was home alone, folding the laundry. I picked up a blue garment and folded it but wasn't sure where the folded item went. The problem? I hadn't seen either the wife or the daughter wear this piece -- it must have been worn over the weekend, when I was in Washington DC -- and wasn't sure whose it was.
In favor of the hypothesis that it was our four-year-old daughter's frock: it had the right length and sported a waist-band. In favor of the hypothesis that it was the wife's: she's recently fallen hard for "baby-doll" dresses.
After turning it over a few times, I realized that the piece of clothing was not 100% cotton, making it more likely to be the daughter's than the mother's. I'll learn in a few days if my deduction was right, or if I should have hung it in our daughter's closet.