Shadowhunters and Downworlders: A Mortal Instruments Reader(29)

It’s worth noting that Cassandra Clare uses the incest taboo as intrigue only. There is no real transgression between Jace and Clary, since they don’t engage in a (voluntary) physical relationship while thinking of each other as siblings. This doesn’t mean that the taboo is less relevant; rather, it breaks the taboo down to its purest form. It’s not an act, it’s an idea. It’s an impression of utter wrongness, an ever-present invisible barrier that attracts at the same time that it repels.





To Incest or Not to Incest? Depends on Whether You Left the Nest


But why doesn’t it repel, in Jace and Clary’s case, any more than it does? Speaking as a reader myself, when it seemed that Jace was Clary’s brother, I blinked a moment, then thought, “So what? You’re in love, and it’s not like you grew up together. Shack up already, and what the heck, have little babies who will be superstrong Shadowhunters with an uncanny talent for the banjo.” It might seem a strange reaction, and indeed it would be easy to become desensitized to the theme of sibling incest with the growing frequency that it is presented in pop culture, most notably cable television. Dexter and Boardwalk Empire both recently introduced incest plots. Showtime’s The Borgias hints at it pretty heavily between brother Cesare and little sister Lucrezia. Perhaps we’re all watching too much Game of Thrones, where sibling incest between Jaime and Cersei Lannister, twins who have been lovers since reaching sexual maturity, is treated largely as a love affair.

Wait, nope. That’s still gross.

So why is watching Jaime Lannister make googly eyes at Cersei so much creepier than seeing Luke and Leia kiss in The Empire Strikes Back? The key is in the phrase “grew up together.” Jace and Clary didn’t. Time to introduce some science.

Sexual aversion to our siblings is often attributed to something called the Westermarck effect, which states that humans are unlikely to view individuals with whom they are raised from a young age as sexually attractive. Whatever it might be called, this knowledge is intuitive to most people. You don’t lust for someone who broke your toys and vied with you for your parents’ attention. Jace and Clary didn’t break each other’s toys. They met as young adults, as strangers. Hearing Isabelle tell Clary that Jace is “damn sexy” and then refer to him as her brother is far more disturbing than an entire book of Jace and Clary’s tortured pseudo-incestuous longing, because they were raised together in the same house as siblings.

Jace and Jonathan have shared an upbringing. Both were raised by the same father, and this is why Jace feels more sibling empathy for Jonathan than for Clary. It’s also why the pseudo-incest that keeps Jace and Clary apart in the first three books can serve as a romantic obstacle rather than being a creepy bucket of yuck.





The Blood Tie


Some might say that the theme of incest in the Mortal Instruments is a nonissue, since it is revealed that Jace and Clary are in fact not siblings but rather that Jace is the son of Stephen and Celine Herondale. But to this I say: Nay. For the better part of two novels—the ending of City of Bones, the entirety of City of Ashes, and a majority of City of Glass—the reader is led to believe that Jace and Clary share Valentine Morgenstern as a father, and this pseudo-incest becomes the main obstacle in their relationship. But is the relationship between Jace and Clary really pseudo-incest? Or is it incest-incest?

When it is discovered that Jace and Clary are in fact not siblings, the romantic in us sighs in relief. Finally! They can be together. But nearly at the same time, the reader is informed that Jace and Clary share the blood of the angel Ithuriel, injected into them undiluted by Valentine when they were still in the womb. With the idea of incest so fresh in mind, this revelation is enough to bring the taboo back to the forefront. One type of pseudo-incest is traded for another. “I gave my blood to Valentine Morgenstern, and he put it in his baby boy,” says the demoness Lilith in City of Fallen Angels, referring to Clary’s biological brother, Jonathan Morgenstern. “You might almost say that in a way, I am Jonathan’s mother.” By the same logic, the angel Ithuriel could claim paternity over Jace and Clary, and we’re back in the incest boat. This new claim asks us to look back over the course of the previous novels; it practically begs us to examine what the blood tie means and the ways it may have influenced Jace and Clary’s dynamic. “Blood calls to blood,” the Queen of the Seelie Court says in City of Fallen Angels. And indeed it does, within the Mortal Instruments series, and elsewhere.

The theory of genetic sexual attraction postulates that we are predisposed to find those individuals with similar genetic material particularly attractive, if this predisposition has not been suppressed by the Westermarck effect. It makes sense. The narcissist in all of us finds similarities attractive. We delight in common traits and preferences. So two siblings who don’t know they’re siblings may find themselves attracted to each other on a basic genetic level. Similar pheromones in an unknown sibling may trigger reactions in the brain, as can similar notes in a relation’s voice. Siblings who were separated at a young age and later reunited often report strong and almost instant feelings of attraction, even euphoric crushes so extreme that it seemed impossible not to act on their urges. This is no small phenomenon; according to an article in the Guardian, as many as 50 percent of these reunions result in strong or obsessive feelings. Couples who break the incest taboo and become intimate insist that the intensity of their relationship trumps every other, that it is heightened by their genetic similarities and can’t possibly exist outside of those similarities. Jace and Clary seem to have this level of affection and intensity. Could it be due to their shared angel blood?