"Ernie and Bert." Hence he grew up hating that name, and also grew up into a bully as a defense mechanism.
Satan is the witches' fatherTheir mother is mentioned but no father, they apparently adore Satan and he's gifted them with magic and the book and even individual powers unique to each sister. They were apparently born into being witches so perhaps each generation breeds with Satan to create the next?
Winnifred's book is made out of her fatherIt explains why he's never mentioned and her affection for it.
Allison is a descendant of the same family as Thackery and EmilyHer mother keeps the museum running and she knows a great deal about the history. also there is a family resemblance.
Allison is a distant relative of the witches.She seems way too keen to open the spell book to check it out, as if she were confident in her own witchcraft powers. Plus, as stated above, she seems to know a great deal about the occult and her family runs the museum and keeps it in pristine condition (even to the point of a particular rat tail being in the same spot even after 300 years when it would have decayed.)
The Sisters became witches because society rejected them.Related to the above edit concerning the Sanderson sisters parentage; their mother either just got around or was a prostitute and had three daughters, each with a different father. This lead to the girls being outcasts growing up and enduring the townspeople's taunts and mistreatment. They learned to keep to themselves and this being colonial Salem, rumors started to spread. Figuring their lot couldn't get any worse, they sold their souls and became witches and go about getting revenge on the people who treated them as less than dirt their whole lives. After a while they genuinely begin to enjoy evil, leading into where the movie begins.