More to the point, it's about how all moms and dads are terrified of their kids — not just of what they are, but also of what they might become. That li'l surgeon you're prepping at nine might one day decide that scalpels are better suited to the unanesthetized.
When first we meet nine-year-old Joshua Cairn (Jacob Kogan), he's not terribly creepy, just slightly off — a nerd-in-training who's just a touch too cold and proper for a boy that age. There's not an ounce of rambunctiousness in Joshua (a superior pianist and brainiac, to boot), not a sign of life in those eyes. His hair perfectly coiffed (à la a New England prep school circa 1958), his skin a pale shade of corpse, Joshua's more a parody of a pint-sized horror-show monster than the real deal. (His musical selections alone point toward dark comedy; the kid appears to have absorbed the entirety of Krzysztof Komeda's oooh-oooh-spooky ouevre.) You get the sense he's more lonely than loathsome — the kind of kid who asks his daddy (a toned-down Sam Rockwell) if he loves him because he's genuinely afraid the old man is losing interest.
And then comes the baby girl — the beautiful baby girl, ready to command the attention Joshua expects and demands and craves. His mother, Abby (Vera Farmiga), can't take her wide eyes off the newborn; Dad and Granny Hazel (Celia Weston, a Holy Roller seemingly left over from Ratliff's career-making doc Hell House) and Uncle Ned (Dallas Roberts, all show tunes and sunshine) can't put her down. So Joshua's left all alone — to dissect his plush toys, mummify his hamster and maybe kill the family dog. And in short order, the Cairns' impeccable Central Park manse is filled with the little girl's never-ending wail, a piercing, unnerving, constant cry that wears on Abby until she looks like her eyes are about to pop out of her head (which, on Farmiga, is already a given).
But what parent hasn't said, "That kid's gonna drive me crazy"? What parent hasn't looked at his or her child and been hit with the sudden, terrifying realization that within the apparently angelic lurks the potentially demonic? Children are remarkably manipulative at a surprisingly early age, and Joshua's merely a big-screen variation on the real thing — a kid who takes great pleasure in freaking out his folks, to the point where one winds up in the nuthouse and the other chains and padlocks everything in the house, even the refrigerator.
Ratliff and rookie co-writer David Gilbert are playing with the conventions of what Pauline Kael called the "horror gothic comedy" when referring to Rosemary's Baby and Psycho; they wrest dark giggles from the apparently overwrought and elicit squirms from the downright hysterical, and even their movie within a movie — Joshua's video documentation of his evil deeds — feels like genre parody. The idea that Sam Rockwell — butched up here as a successful Manhattan moneyman with a racquetball fetish — could be scared of this kid is laughable. It's just a sick joke shared among parents once the kids are down and the drinks are poured. Joshua's no demon incarnate at all, just a spoiled and petulant child working some Upper East Side hoodoo.
Ultimately, the movie builds toward its rather brilliant punchline; this "horror" movie ushers you out of the theater laughing — and that's its intent too, not the accidental effect of creep show theatrics pushed too far or taken too seriously (as they were in the dismal Birth, to which Joshua will get too many unfair comparisons). Turns out the devil just doesn't like his parents.