Oh boy, I couldn't even begin to guess. Apparently people think if it's Pete, he's had a sex change because the other baby is supposed to be a girl, but I could see Ryan Murphy going that route. Other suspects...man, idk. The list is SHORT now. Wes (Grace's dad), maybe even Grace (she finds out she has siblings, wants to get close to them and helps them kill), and...idk! Pete, haha. Those are the only options at this point.