WHY KIDS ARE DISGUSTED AT THE THOUGHT OF THEIR PARENTS HAVING SEX

by

REBECCA COLLINS

_________________________________________

Rebecca Collins is a freelance writer/editor.

 

 

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The silence that descends when the topic of parental intimacy comes up is a universal truth. You see it in the cringe of a teenager, the swift changing of the subject, or the desperate, frantic need to un-see a mental image. It’s a visceral, localized reaction, a "yuck" factor that ignores borders and cultural divides. While we tend to brush it off as typical adolescent awkwardness, this isn't just about being a kid. It’s buried deep in our evolutionary bedrock. The disgust young people feel isn’t just a social habit; it’s a hard-wired psychological guardrail designed to keep the family structure from collapsing in on itself.

To understand why this happens, we have to talk about the Westermarck effect. Back in the late 1800s, Edvard Westermarck realized that humans have an internal alarm system triggered by people we grow up around. It’s a biological fail-safe. By defaulting to a state of sexual disinterest toward those in our immediate circle, we effectively prevent the genetic disaster of inbreeding. That’s the evolutionary logic. But it does more than just act as a genetic gatekeeper; it builds a mental wall. Our brains are conditioned to view parents as architects of our safety, not as sexual beings. Once that category is broken, the brain panics.

Think about how a child views their parents. They are the gods of the household—the providers, the protectors, the ones who make the world stable. This hierarchy is fragile. If a child is forced to suddenly see their parents as autonomous adults with private, sexual needs, that entire internal architecture wobbles. The disgust is a defense mechanism. It’s the brain trying to slam a door that shouldn't be open. We aren't disgusted by the parents themselves; we are disgusted by the destruction of the mental order we relied on to grow up.

Freud called it the "primal scene," and while his theories often get a bad rap, he hit on something vital here. The sheer, naked reality of parental intimacy forces a kid to face an uncomfortable truth: their parents have a life that doesn't include them. It makes the child feel small, excluded, and terrifyingly dependent. That jolt of exclusion is painful. The disgust serves as a protective layer, a way to shove that unwanted reality back into the shadows and keep the world feeling simple, predictable, and safe.

There’s also an evolutionary push toward independence hidden in this aversion. When kids hit puberty, they need to leave the nest. They need to find partners outside their own bloodline to keep the species moving forward. If we didn't feel a deep-seated, instinctive "no" regarding our parents, the transition into adulthood might feel a lot muddier. This repulsion actually nudges the adolescent outward. It acts like a psychological compass pointing away from home, directing that sexual energy toward peers and the wider world where it actually belongs. It is a necessary friction.

Cultural norms pile onto this, too. Societies have spent millennia building high, thick walls around the concept of parental privacy. We don't talk about it. We don't acknowledge it. We treat it like an untouchable, forbidden zone. That silence isn't an accident. It’s a reinforcement of the biological taboo. When a kid learns that this is a subject meant to be avoided at all costs, their instinctual reaction becomes a badge of honor. It’s the sacred, sealed chamber of the family, and we’re taught, almost subconsciously, that we don't have the key—and we shouldn't want it.

This taboo serves as a cohesive force for the family unit. In many hunter-gatherer societies, the preservation of the parental pair-bond was essential for the survival of the offspring. If the child were to interfere, or even if the child were to become a source of sexual confusion or conflict, the entire structure of the household would suffer. By enforcing a strict boundary—a barrier of silence—the culture ensures that the parents can maintain their relationship without interference from the children.

We should also consider the cognitive load involved. Developing a human brain is an incredibly expensive process, nutritionally and energetically. A child’s brain is designed to focus on learning, social imitation, and survival. Adding the complexity of understanding adult sexuality into that mix would be an enormous, unnecessary distraction. Disgust acts as an efficient filter. It allows the adolescent to dismiss that information, keep their brain focused on the tasks of maturation, and avoid the overwhelming emotional chaos that would come from attempting to navigate the complex social landscape of their parents' private lives.

So, don't write this off as just a weird phase or a bit of priggishness. This disgust is a masterfully efficient survival strategy. It’s a product of millions of years of selective pressure, woven together with our deep, primal need to feel safe within the family unit. It forces us to grow up, to look outward, and to preserve the sanctity of our own developmental history. That "yuck" isn't a glitch in the system. It is, quite literally, a feature of what makes us human. It is the way our brains keep our childhoods locked in a state of purity, protecting the foundations we build our lives upon. We are creatures of habit and biology, and this reaction is one of the most reliable, constant threads in the tapestry of our shared, evolving existence. It is the quiet, reflexive guard that stands at the door of our childhood, reminding us that some things, for the sake of our own growth, are meant to remain unseen.

Given these deep-seated evolutionary roots, one must wonder if our more open discussions about sexuality in the home are actually helping teens, or are they inadvertently triggering this protective, biological "alarm" more often than we realize.

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Arts & Opinion, a bi-monthly, is archived in the Library and Archives Canada.
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