I remembered last year there was a picture thread like this and there was a girl who used someone else's pic but edited the text that was written in the piece of paper she was holding.
I think what Kathryn is trying to say is there's no way to definitively prove it's you unless of course you see that person through video chat or in person.
However pictures with actual writing on a piece of paper are more definitive definitely then a picture without or a picture with just text on it.