Sugar and knives and demons and strife, that's what horror children are made of, but why do their adorable, bloodthirsty little faces never fail to chill our blood and make us more jumpy than a flea on meth with its feet on fire?
The psychological reasons why kids in horror (or real life, in certain chilling circumstances) creep us out so much are embedded deep, deep within the reptilian part of our psyche, and I am going to attempt to break them down with the expert help of horror directors and writers below.
The Destruction Of Innocence
Children are 'innocents.' So the more they stray from that, the more frightening it is for all of us. For an innocent energy to be 'taken over' is the gravest of abominations the world can reap upon us. Adults are expected to be corrupt and evil, in a way. Children are the last hope for good. — Dee Wallace Actor, 'The Hills Have Eyes', 'The Howling,' 'Cujo,' 'The Frighteners'
The most simple reason why children scare so much is that, compared to adults, who we see do unspeakably evil things on the news daily, kids are meant to be pure.
While most horror movies stray away from the territory of murdering children and literally wiping innocence off the face of the earth (of course there are plenty of exceptions), there is another way to eradicate what makes children a sign of hope and goodness, and that is by making them murderous little psychos.
By making a child possessed, we ultimately lose the real innocent figure and make a subconscious connection with the ultimate act of corruption: The murder of a child. Sublimating this primordial horror into a childhood that has somehow become toxic or corrupt is, in a way, a safer way to present this.
I also think that, in many ways, children aren't quite 'civilized' people; they're unpredictable — we never know exactly who or what they are or what they're going to do. We don't know if they quite have empathy yet — or if they are going to play by social rules (or even know the social rules). They're kind of anarchic forces — and anarchic forces make great horror.
— Dawn Keetley, Ph.D. Associate Professor of English, American literature, the Gothic, Horror Media, Lehigh University
You know how a toddler you have been put in charge of will merrily go up to a nice little old lady and tell her all about her 'big fat mustache?' It is the same lack of social conditioning that makes children in horror so damned scary.
While adults know the appropriate social boundaries in life, kids are still learning them and when a poltergeist decides to nest in them, who knows what they are going to do with those scissors.
The creepy/murderous child trope goes back to 'The Bad Seed,' from the most kid-centric decade, the 1950s. But lately it's been having a resurgence, with movies like 'Goodnight Mommy' and 'The Boy,' just to mention a few of the latest entries.
Could it be connected to the fact that more and more parents have difficulty balancing work responsibilities, child-rearing, and elder care (not to speak of nurturing their own relationships, personal and career aspirations) and are squeezed financially by the costs of raising children and taking care of their own aging parents? Therefore, is it any wonder that children in genre movies are portrayed as powerful, disruptive, and uncontrollable? Perhaps these menacing moppet movies reflect the fears inherent in helicopter parenting — that the minute you take your eyes off your child, something dreadful will happen.
— Joe Dante Director of 'Piranha,' 'Gremlins,' 'The Howling'; Co-founder, Trailers from Hell and The Hollywood Horror Museum
Evil children don't get much more sinister than when they plunge a cleaver into their once-loving momma's face, and the betrayal of this ultimate bond between parent and child is immensely powerful.
This scenario feeds into the idea presented by Joe Dante above that parents can feel overwhelmed by their children and feel like their moral corruption is their fault, meaning a crushing blow of guilt that is dealt along with their untimely death. One memorable occasion being in Night of the Living Dead where Karen's mother seems to almost willingly sacrifice herself to her bloodthirsty offspring.
But Why Are Little Girls The Creepiest Of Them All?
Although there are a few bad boys (in the most literal sense of the word) in horror such as The Omen's Damien and, more recently, the little boy shrouded in the potato-sack mask in The Orphanage, haunting adults is overwhelmingly a girl's world, but just why do these ruffled ragamuffins seem to hold the secret key to our deepest fears?
There are a couple of (obviously, very sexist) reasons why Regan MacNeill might pack a bigger psychological punch that say Gabe of Pet's Semetary that we will explore below.
A Bewitching Legacy
Girls may be seen as somehow closer to 'nature' — further from 'civilization' than boys. (Anthropologist Sherri Ortner has a famous essay about how, cross-culturally, females are closer to nature than males and that this makes them more of a 'border figure' —potentially more threatening.) And it is often girls who become possessed, grow up into witches, etc. The boundaries of their 'selves' just seem more permeable than boys. I would say the water that's always flowing when Samara [from 'The Ring'] is around represents these permeable borders. — Dawn Keetley, Ph.D. Associate Professor of English, American literature, the Gothic, Horror Media, Lehigh University
Since Biblical times, women have been represented as the weak, treacherous, and lustful sex who is more insidiously dangerous than men, who are, by contrast, also done a disservice by being represented figures of more naked, animalistic aggression.
From this legacy, women have been seen as the mistresses of witchcraft, magic, and the harnessers of mysterious forces that men might not be able to access, perhaps through the mysteries of their bodies which are capable of childbirth etc.
Unfortunately, girls are still taught to be polite, quiet, and likable instead of confrontational, aggressive, and sometimes even rebellious individuals. So when little girls are depicted as monsters, it's effective because they are expected to be harmless, and it upsets people when they are not. It's an antiquated, but persistent social paradigm that negatively affects girls and women.
Jovanka Vuckovic — Writer, director, 'The Captured Bird,' 'XX'
Societal norms teach us that little girls are essentially unthreatening, innocent little flowers who would never dream of the bug-torturing, mud-wrestling antics boys get up to. Obviously, this is bullshit (big up to all my ladies who spend their childhoods crawling around in bushes hunting for spiders!), but stereotypes like this lurk deep within the darkness of our subconscious.
Perhaps one the things about The Exorcist that really sticks in people's minds, for example, is Riley's obscene provocative sexual behavior in the infamous crucifix scene. Whereas teenage boys are regarded as unstoppable masturbation machines in a kind of teen-movie 'lol' way, the sexuality of girls is seen as way more threatening and 'unnatural.'