Actually as can be seen by my four star rating, I liked the film. All the acting was great, and I suppose the cinematography was great too.
Typically in a horror film we root for the final girl or guy or whatever. But in this one, after Charlie is killed in an accident in which her brother was highly contributorially negligent, it was clear that there would be no recovery for the good guys. You can't recover from that. Ignoring the supernatural stuff for the moment, this movie details the events that relentlessly slam a family until it breaks. A family that's had it tough has it even tougher and basically succumbs to a very evil fate, despite their not really being bad people and even the mother's attempt to sacrifice herself for her son who she tried to miscarry. Self sacrifice usually works, but not here.
The grandmother was not well liked, even by her own daughter (the 'mother' annie). She was 'always right' and aloof and just a pain in the ass. Towards the end she had dementia apparently.
The son Peter and his mother Annie had a really bad relationship. Annie confesses to Peter that she did 'all the things' that were popularly supposed to cause a miscarriage, but they didn't work. She didn't want to have him, but did anyway. Annie also was a sleepwalker and one night she awoke while standing over a bed in which her husband and young son Peter were sleeping, they being drenched in flammable paint remover, and her holding a lit match. This parallels Annie's attempt to burn a sketchbook that has become something of a "horcrux" to borrow from the HP mythos in that it has some spiritual/physical connection to the person who is currently possessed by Paim. She drenches it in lighter fluid and throws it into the fire, but it is her husband who has been possessed at this point, so instead of Annie being consumed by flame, her husband is. However, Paim clearly escapes the husband and enters Annie's body. Now, if he could do this, enter a body at will, then why does the coven have to drive Peter's soul out of his body so that Paim can inhabit it? Why does paim need the coven at all, appart from them getting somebody to read the incantation? Also why does Annie, being possessed by Paim, chase Peter around the house--why can't Paim just cross over to Peter? Well one answer that would fit with all of these complaints is that Paim cannot escape a host until it dies, or perhaps as it dies. So given that Paim was in Charlie since her birth, Charlie's death was required before Paim could escape and enter a new host. We are also told that Paim seeks the weakest person available, and prefers males since his essence is male. Still makes no sense for Annie to chase Peter, and all the two references to Peter potentially losing his head like other characters in the film don't make sense since they want to preserve him for Paim. However, the coven leader indicates that they made a mistake by putting paim in Charlie since she is a girl (they wanted a boy). So they 'correct' that mistake by killing charlie. Where does Paim go after that? Ie what's the chain of custody on Paim's spirit--it's broken after Charlie and he next enters, apparently the husband at some point. That's why the husband won't consent to burn the book for Annie, because he's actually possessed by Paim and burning the book would drive him out of his host. But now we must realize that when Annie goes to burn the book for the first time and she catches fire, that means that Paim was in her then. But we know paim doesn't like to be in women, so at some point he gets out and into somebody else. Maybe I missed it but he must get into the husband at some point. Maybe there's some indication of this in the shot we get in the husband's office when he's drinking whiskey.
The miniature making thing is clearly stolen from that peter dinklage film. If this vision is so original, why does it steal from Rosemary's baby and the peter dinklage film? And the miniatures didn't really get involved in the plot at all, they were just showing us what Annie was obsessing over.
What did heredity have to do with anything? Well, I believe the answer to this is provided by one line in which Annie proclaims that she's discovered that she is a medium. I guess not just anyone can carry off a seance. And she then inherited this from her mother, and judging from the poster, Charlie inherited it from her. Oh, how the heck did Annie's mother manage to breast feed charlie? whatever.
Why did Annie try and miscarry Peter, and later attempt to burn him alive? Because she knew at some level that he would become the host for Paim.
the beheadings. They are probably a way of killing a body without allowing its soul to go anywhere. Charlie's beheading: Ostensibly charlie had an alergic reaction to some walnuts that were in the chocolate cake at the party. Charlie loves chocolate, and they made chocolate cake with walnuts, which she is alergic to. Sounds like a plan. So when her throat swells up and she's struggling to breath, she sticks her head out of the car as Peter is speeding to the hospital. There is a deer dead in the road and when Peter swerves to avoid it, charlie's head strikes a lamp post and she loses her head. While it appared that Peter was grossly contributorily negligent in charlie's gruesome death, it's made clear that it was the will of the coven. The coven's symbol is shown on the power post that charlie's face smashes in to.
The grandmother's beheading: the coven dug her up and placed her in the family house in the attic so that she would be there during the seance, which requires all the family members. I would assume just the living ones, but this must have added something. the body was there but the head was missing. The missing head apparently allows the spirit of the dead person to take their place among the demons, in hell or whatever. The severed head is associated with royalty. Maybe charlie became a princess?
Annie's beheading: Annie is possessed by Paim for a time after her husband bursts into flame. During this time she pursues Peter but he evades her. Not sure why she pursues peter since killing him would make him unavailable as a host for paim. Maybe she just wanted to subdue him. But after peter goes to the attic and sees the location where the body of his grandmother was, and sees some other spooky stuff, he sees his mother up in the rafters, apparently she got in through some break in the roof. She's steadily sawing off her own head with wire. After Peter sees some spooky naked coven people, he dives out of a window and falls into the garden below. As he lays there motionless we hear Annie's head sever and hit the floor. Peter comes to and sees his mother's body carried through the air to the tree house near the family home. He follows it and climbs up to find the coven (both live and dead--his mother and grandmother are also prostrate before the christ-looking king figure there) there prostrate in reverence for some royal of hell. One of the living coven members places a crown on Peter's head and speaks words to Paim indicating that this is the new host they have gotten for him. So... the point is that upon his mother's self beheading, Paim was freed from her and he entered Peter.
Peter's beheading in Annie's dream: earlier peter had a dream in which arms emerged from behind the headboard of his bed and were tugging at his head, apparenlty trying to decapitate him. He wakes to find his mother standing near his bed. though he accuses her of doing this she was too far to have been doing it, we think. Anyway Annie herself has dreamt that Peter's head was severed from his body and covered with ants, like Charlie's was after he beheading. Maybe this represents her last ditch effort to keep Peter from hosting Paim--beheading him. But it only occurs in a dream.