Triplets Puzzle - Solution
The Puzzle:

Victor, an old friend of the family's, came over one day and as usual he didn't know who was who, so he asked each of them one question.
Victor asked the sister that was sitting on the left, "Which sister is in the middle of you three?" and the answer he received was, "Oh, that's Sarah."
Victor then asked the sister in the middle, "What is your name?" The response given was, "I'm Sally."
Victor turned to the sister on the right, then asked, "Who is that in the middle?" The sister then replied, "She is Sue."
This confused Victor; he had asked the same question three times and received three different answers.
Who was who?