This test is totally flawed, since when is using logic the sign of a psychopath? It's obvious that she might have thought the man was there because somehow he was related to the mother, thus also very likely related to the sister. Just because you can see this pattern, does not necessarily mean you would do the same thing she did, if science really worked this way we'd still be in the stone age
I'm hoping you're joking, if not then THAT's the real sign of a psychopath