How many questions would you need to differentiate between identical twins, particularly if they live and work together? Take identical twin sons of a subsistence farmer - they live together, work together on the same things, know the same people, have the same genetic makeup, and whichever was the first twin born may not have been recorded. You could ask their names, but that's not a yes/no question.
Or even twins who are still babies, no work required? Some cultures wouldn't even have named them yet.
Multiple births would be bad enough, and then you have people with dementia who can't remember the answer to most of the questions, and people in a coma who can't answer questions at all. The chance of succeeding with this exercise is approximately zero.
Or even twins who are still babies, no work required? Some cultures wouldn't even have named them yet.