Whenever someone meets me and my twin sister Meredith, the first question they ask is “who’s the evil one?” followed by “can you read each other’s minds?” They attempt to distinguish us from one another, pointing out our similarities and differences: she has lighter hair, a smaller nose, blue eyes; I’m shorter, with dark hair and hazel eyes.

Even though we’re not identical, we’ve been referred to as a unit since birth: “the twins are doing this,” “the girls are going there.” We shared a room, wore similar clothing, were in the same classes, played the same sports and had the same friends. We were a package deal—if you invited one twin to a birthday party, you needed to invite the other. We’d probably never spent more than twenty-four hours apart until we were seventeen, when we went to universities in different cities. With that separation came the realization of how strongly tethered we were to each other, an experience of the world that most people do not share.

It’s both jarring and compelling to see two people who look exactly alike, who seem to have such an impenetrable connection. The concept of the twin has built up in our “cultural genes,” says Marcel Danesi, who teaches semiotics in the Department of Anthropology at the University of Toronto. Twins feature prominently in many folktales and religions, and in modern storytelling, we’ve become familiar with certain twin archetypes: in comedies, twins play tricks on people and swap places; in horror, their presence is ominous, threatening and creepy. They’re either identically good or bad, or foils—one hopelessly angelic, the other unspeakably evil. And they’re frequently fetishized, treated as a sexual curiosity.

In Sigmund Freud’s 1919 essay “The Uncanny,” he explores symbols and objects that are strangely familiar, yet “evoke fear and dread.” These symbols include strange patterns, accidental or unexpected repetition, doppelgangers, a puppet that looks at first like a live person—and, of course, twins. Because we look so much alike, writes Freud, people think that twins are capable of “what we would call telepathy—so that one becomes co-owner of the other’s knowledge, emotions and experience.” Twins upset the norms we’re hardwired to understand by presenting an unsettling alternative to the individual.

“Our uniqueness is kind of politicized, it’s legalized,” says Adam McGee, who taught cultural studies and anthropology at Tufts University. “The idea that there might be somebody else who is exactly like you is very uncanny and kind of uncomfortable for us, although it’s also fascinating.” With that fascination comes distrust.

A significant number of twins and clones appear in the first few seasons of The X-Files, the Sweet Valley High series ran for two decades and published six hundred books, and the evil twin is a staple of soap operas—but our presence in horror has always interested me the most.

One of the most famous examples is the Grady twins from The Shining. They dress the same, they speak in monotonous unison, they hold hands and appear as a unit. There’s no denying they’re scary, especially since the camera cuts between showing them standing in the hallway to lying dead and bloodied on the carpet. But there’s nothing inherently interesting about them—they’re just two of the many malevolent ghosts wandering the halls of the Overlook Hotel. Though the film itself leaves them behind fairly quickly, their image has become ubiquitous in pop culture—a testament to how memorable and unsettling viewers find their presence.

A typical, if especially egregious, example of the twin tropes can be found in 1971’s Twins of Evil, part of a schlocky vampire trilogy. After the death of their parents, beautiful twin sisters Maria and Frieda move from big-city Venice to live with their uncle Gustav, played with surprising sincerity and depth by Peter Cushing. Gustav is pious but tyrannical, running around their small, seventeenth-century town burning women dubiously accused of witchcraft. He’s not particularly welcoming to the twins, played by Playboy Playmates Mary and Madeleine Collinson. They fit cleanly into the virgin-whore binary: Maria is sweet, chaste and easily frightened, while Frieda is mean, lusty and adventurous. Leaning on Freud’s concepts of scary twins, they play up their twinness by wearing identical, precariously low-cut dresses, and they’re telepathic, able to feel the other’s pain.

Frieda becomes enamoured with the mysterious, womanizing Count Karnstein, an unintentionally ridiculous portrayal by Damien Thomas. Maria begs her sister to stay in at night instead of sneaking off to see the Count, but Frieda is adamant, threatening to hurt her sister if she rats her out to Gustav. The Count turns Frieda into a vampire, who then begins to seduce and feast on local townsfolk.

The suggestion of abuse within their twinship is a missed opportunity for surprise and complexity—to most people, twins are supposed to be best friends, close and loyal. Unlike their uncle, who is eventually forced to question the speed and certainty with which he executes witches and vampires, the twins don’t have a rich inner life or characterization; they’re just pretty props, offering the writers the opportunity to toss in gross off-hand comments to punctuate the action (“Twins! That would be something different,” a leering Count Karnstein announces early on). Even when she’s evil, Frieda doesn’t say much or betray any particular motivation. And the twins never face off. It’s Gustav who deals the deathblow to Frieda, when it would have been more interesting for the sisters to have a final showdown—Maria isn’t even there when her sister is killed.

This is what the worst of the genre tends to do: flatten an intriguing concept in favour of blood and gore, jump scares and objectification. The best horror films delve more deeply into the symbols and concepts that frighten us, eschewing the easy and the sensational to explore something richer and therefore much more terrifying.

Twins don’t run in my family, and my mother’s pregnancy was a surprise. At thirty-seven, she already had two young kids and a teenage stepson. My mom likes to say that my dad’s hair turned grey the day he found out.

Meredith and I were inseparable growing up, and often experienced shared, or false, memory—when one twin experiences something but both are convinced it happened only to them. My sister often accused me of “stealing her memories” for the sake of a good story until we later learned that it’s a frustratingly common phenomenon in twins. One theory for why this happens comes down to a family’s natural affinity for telling stories about themselves to each other. Since twins look the same and do many of the same things, family members often mix them up when retelling events. This collective misremembering within the family unit leads to confusion—it all gets muddled.

Despite our closeness, we’ve always been very different: she’s bubbly, charming and brash, while I’m reserved, measured and quiet. At times, we’re heavily reliant upon each other, but can quickly swing to being competitive or resentful, then back to supportive and caring. Years of living apart have widened the differences between us, which is good for our personal senses of self but excruciating when it comes to conflict. I expect Meredith to think the same way I do, and it’s a painful shock when she doesn’t.

This kind of complex twin relationship is ripe territory for storytelling and for horror, though it’s rarely seen on screen. One example is American Mary, a fun, gory film written, directed and produced by Vancouver-based twin sisters Jen and Sylvia Soska. In a cameo appearance, the sisters play the Demon Twins of Berlin—sisters so close they get their arms surgically swapped so they can forever remain connected. While the arm-swapping is obviously over the top, the characters can be read as a metaphor for how twins sometimes feel about each another. The Soskas get asked the same questions my twin sister and I do—they call it the “twinterview”—and much of their work involves twins. Their films portray something that has come to be a rarity: their twin characters have distinct personalities and are not simply good/evil foils.

Another standout comes in 2014’s Goodnight Mommy, where twin boys Elias and Lukas are exactly alike in every way, and creepily whisper to each other before answering questions. (Unlike the twins of The Shining, their relationship is explored in detail, leading to a rich, nuanced representation.) When their mother returns to their isolated home in the Austrian countryside from getting plastic surgery, she’s acting strangely: she’s cranky, her face is entirely wrapped in gauze and she eats bugs in her sleep. She only makes food for Elias, punishes Lukas more harshly, and gets very angry when Elias defends Lukas, or insists that she also make him food. Perhaps most disturbingly, she keeps trying to separate the twins. The twins begin to suspect that their mother has been replaced by a demonic imposter and, finally, decide to kill her. Despite their violent actions, and (spoiler alert) the film’s eventual reveal that Lukas is a hallucination of Elias’s dead twin brother, I was rooting for the boys the whole time. The thought of someone trying to separate you from your twin, despite all your differences, is horrifying.

My all-time favourite portrayal of twins appears in David Cronenberg’s 1988 film Dead Ringers. Identical twins Elliot and Beverly Mantle (both played by Jeremy Irons) are sophisticated, celebrated gynecologists who live and work together, eat the same food, sleep with the same women and tell each other everything. Their lives are set against the beige backdrop of a dusty 1980s Toronto, filled with turtlenecks and loose trenchcoats. In public, Beverly takes a backseat to his overbearing brother, and Elliot impersonates him whenever it’s convenient.

When shy, sweet Beverly refuses to share his new girlfriend with confident, obnoxious Elliot, it enrages him, even though Beverly is just trying to be normal. The brothers’ relationship grows tense, leading to stress for Beverly—gruesome nightmares come first, then self-medication with drugs. Beverly soon becomes addicted, but not before he makes a few deeply disturbing gynecological errors in their shared, bright-red operating room.

Elliot attempts to fix everything by taking the same drugs as his now-disgraced brother. “Beverly and I just have to get synchronized,” he explains. “Once we’re synchronized it will be easy.” Elliot’s plan fails, and they both soon end up dead. Their separation was crucial in order for them to lead individual lives, but they were so interdependent that their attempt proves fatal.

The film doesn’t fall into any twin tropes—neither Beverly nor Elliot is good or evil, virginal or promiscuous; they’re both complex and flawed. Their twin relationship is believable because they’re sometimes dependent on each other, and at other times repulsed. They simultaneously support each other and hold each other back. Their end is tragic and hyperbolic, but it’s emotionally honest.

TV and film portrayals of twins give me insight into how people perceive the relationship I have with my sister, and why we face the same questions over and over again. Because these portrayals so often lean on tropes, non-twins receive partial or inaccurate ideas of twin relationships, like seeing a figure through frosted glass. Good storytelling, on the other hand, can utilize the fun and creepy aspects of twins to depict realistic, if twisted, twin relationships. If these depictions reigned in horror, my sister and I would no longer regularly be asked who the evil one is—instead, friends and strangers would understand that we both contain the capacity for light and dark, and experience the shock of both intense closeness and difference.