Twins are creepy.
Whether they're staring through the TV screen during a rerun of a 1980s horror flick, or marketing the newest layered ensemble for the 'tween market, twins are undeniably, inexplicably creepy.
It's the creep and fascination factor that has begun to see the twin crawl from her place as the archetypal blank-eyed freak show or overly sexualized blond-bombshell bad girl, and move onto the bestseller list.
26A, a coming-of-age novel about a set of female twins who have to cope with family, separation and independence, won author Diana Evans the Orange Prize for promising women writers.
Edward Carey's novel Alva and Irva was published about a year ago. It documents one sister's struggle to draw her twin out into the world, enticing her with a tiny model of their hometown.
Lori Lansen became fascinated by the lives of twins while doing research on a screenplay about unusual bodies. Conjoined twins held her attention.
"[It's]the intimacy of conjoined twins," she said. "That's what I found to be an interesting thing.
Lansen's book The Girls, excerpts of which are being published in serial form in The Globe and Mail this week, is about twins joined at the head. The novel is slated to be in bookstores by the third week of September.
"Ordinary twins are usually very similar," she said. "They have similar lives and pursuits. Conjoined twins on the other hand can have very different personalities.
"It's like the struggle for individuality is so profound and intense for conjoined twins because they're often perceived and treated as one person. They must struggle so fiercely that they choose different personalities."
Twins in literature are usually female. In popular culture, one "good" twin fights her "evil" sister, or they are both portrayed as evil.
Rarely are both considered "good."
Ken Follett's thriller novel, The Third Twin, published in 1997, was one of the rare ones to deal with male twins. In that novel, the protagonist, who faces the doings of his evil murderer twin counterpart, must come to terms with whether his actions are determined by his shared DNA, or if his separate upbringing is responsible for his identity.
Lansen said she was fascinated by the prospect of having two people from the exact same origin, who shared one cell in the womb.
"What is it like to share your life in such an intimate way?" she asked. "I was fascinated and drawn to these characters, who shared devotion, empathy and even telepathy."
Books about twins aren't new.
Among the most famous literary twins are the Antipholuses in Shakespeare's The Comedy of Errors. In the play, they were used as a plot device to spread discord and hilarious confusion.
The prank potential of having a mirror copy has not been lost in modern times, either.
The most current double princesses of pop culture, Mary-Kate and Ashley Olsen, have spawned volumes of fluff and flowery prose for preteens, often reminiscent of Nancy Drew or Hardy Boys classics.
And before the dimpled cheeks of the Olsens beguiled TV audiences more than a decade ago on the TV sitcom Full House, a generation lived and loved alongside bookish Elizabeth and outgoing Jessica in the Sweet Valley High book series.
"They're so damn freaky," Edward Carey said of twins as a whole. His book deals with the personal differences between two people who look alike, and their struggle to stay together while pursuing separate lives.
He said he got the idea for his book because his grandmother and great-aunt were identical twins. He said he used to sit across from them and try to spot differences.
"Can you ever really get into a twin's life if you're not one of them yourself?" he asked.
Carey said twins are frightening because they share a self-sufficiency foreign to most single-born people.
"There's something so desperately private about their world," he said. "It's very detailed and quite frightening."