The unnamed and mysterious sources told Kotaku that the Big Sisters will be some ?Amazonian versions? of Big Daddy. And the rumors seem to be backed up by the BioShock 2 teaser website I’ve already told you about, since the news clipping there told us about the kidnapping of a Little Sister and the description of the attacker was that of a different Big Daddy: it had incredible speed, was thin and tall, and wore ?some kind of red light?.
Of course, these could only be considered speculation and, although it might prove that everything is true, we should wait for 2K Games to officially confirm the existence of Big Sisters in BioShock 2 before getting too excited (or not).