Do we know yet how Ingrid became evil?

Was it due to the betrayal of Gerda? Like maybe while she was in the urn, she had time to think about how Gerda betrayed her and called her a monster and then trapped her in the urn? 或者 is it possible Ingrid has been freed once before Hans freed her and she was put back in? Another theory of mine is that Ingrid came in contact with an evil mirror similar to the one she has now if not the same mirror that she now that changed her.