The TV Examiner discusses how Jennifer is the "Child of Ruin" and may in turn be the child of Audrey and William.
In Friday's episode "Monster's Ball" Jennifer and others that share her birthday June 12, 1981 are being destroyed by the werewolf like creature. As Jennifer and the group try to fight the creature, Jennifer finds a book that she said was left at her parents' home. She holds it up and Audrey recognizes it as a book that she gave her FBI boss, "Unstake My Heart". As the monster attacks Jennifer holds the book and it destroys the monster.
Later as she opened it she saw that she was the "child of ruin" and that she could send evil back through the portal. Would this mean that since Audrey began the troubles and "ruined" Haven and that William is evil and is trying to kill Jennifer that she is their child?
Maybe this connection is why William and Audrey are connected and Jennifer could hear them in the barn and maybe this is why she doesn't know her true parents.