'Can I Get Rid of My Own Shadow?’: When Twins Try to Murder Each Other

In June, a Floridian yoga teacher appeared in court charged with the second-degree murder of her identical twin, Anastasia. Prosecutors allege 37-year-old Alexandria Duval (also known as Alison Dadow) intentionally plunged their car off a cliff in Hawaii. Witnesses saw the pair "screaming and arguing with each other" and allege that Duval made no attempt to brake during the crash.

We've long assumed that twins are each other's best friends, and popular culture rarely suggests otherwise. From The Parent Trap and Mary-Kate and Ashley to the chain-smoking pair Patty and Selma in The Simpsons, twins have long been touted as soulmates from birth.

As an identical twin, I've always felt closer to my twin than my older sister. It's led me to question whether twins naturally share a stronger relationship than their non-identical brothers and sisters. "Twins have many more similar experiences than your average siblings," explains Dr Avidan Milevsky, a psychologist and author of Sibling Issues in Therapy. "The similarities between them often create a certain bond that is unrepeatable in other sibling dynamics."

Tracey Sutherland, 27, a Massachusetts preschool teacher, agrees: "There's a loyalty twins have with one another. It's an inevitable inner circle that no one else gets to be a part of. As crazy as it sounds, we truly are one half of each other—but at the same time we are our own person."

"My husband think it's so weird that any memory that I share from my childhood, I start by saying 'we', never 'I,'" adds fellow twin Kim Outhouse, 29. "Everything that I did as a child also included my twin."

Unsurprisingly, research has found that more twins remained unmarried than singletons, with one study concluding that this "might indicate that twins do not have the same need for marriage" as their non-twin counterparts. Couple this with other research that finds the loss of a twin is more intense than those of other relatives, it's little wonder that twin murders appears all the more extreme—and bizarre.

But while sibling rivalry is something pretty much all families have to contend with, what exactly drives one twin not just to seek to separate and surpass the other, but to permanently and violently sever that familial bond?

Despite provoking morbid fascination and horror in equal measure, twin murder is certainly not a new phenomenon. In ancient mythology, the destructive power struggle between twins has its roots in the story of Romulus and Remus; the former killed his twin after he criticized a wall that Romulus had built around his city.

More recently, in 1998, San Diego resident Gina Han masterminded a botched murder plot against her twin, sparking international headlines and later becoming a favorite storyline on true crime shows like Snapped. Just last year, Robert Cerqua from Hampshire, UK, was found guilty of stabbing his twin brother to death on New Year's Eve. (A brief overview of the history of twin killings suggests that non-identical or fraternal twin murders seem to occur less than those committed by identical twins, but this may be because these less sensationalized cases tend not to make the headlines.)

Milevsky attributes wanting to murder your twin to a host of factors that go "way beyond" standard sibling rivalry dynamics. "Classic sibling dynamics may be a small element within this disturbing phenomenon but at the core, actually killing a sibling is driven by the killer possessing severe psychopathology and psychosis," he says. "Add to this severe psychopathology, the competition that is often found in twin relationships, and you may then find a case of twin killing."

You might assume that having this twin bond would add to their sense of grief. However, this isn't quite the case. Twin loss expert and author of When Grief Calls Forth the Healing Mary R. Morgan says that guilt often follows relief. "Relief can also surface at the end of a complex relationship, especially when there is a conflicted 'personal identity versus twin bond' issue."

Rather than viewing it as a macabre act, could murdering a twin in fact be an act of liberation? "Some twin pairs—not all—become disillusioned about their twinship because they struggle to be 'known,' not just 'noticed,'" twin expert and The Same but Different author Dr Joan A. Friedman explains. "Since outsiders relate to them as a unit, they expectedly have conflicts with their twin in an attempt to define their individual selves. Rivalry in adult twins has everything to do with wanting to be on one's own and discovering one's sense of self without worrying how this will disrupt and upset one's twin."

While she says that most twin pairs eventually find ways to define their identity, some twins aren't so lucky. Just take the case of Welsh twins June and Jennifer Gibbons, dubbed the "Silent Twins" due to their secret twin language and selective mutism. After a crime spree of arson and theft, the then 18 year olds were sent to Broadmoor, the UK's highest security psychiatric hospital, where they both became convinced that in order to experience true freedom, one had to die.

Entries in June's diary give some inkling into her torment at how their twin bond trapped them: "Nobody suffers the way I do… This sister of mine, a dark shadow robbing me of sunlight, is my one and only torment."

Jennifer agreed, writing in her own diary: "We have become fatal enemies in each other's eyes," but she questioned if she could ever live without her twin. "Can I get rid of my own shadow? Without my shadow, would I gain life, be free or left to die?" Eleven years on, just as the twins were due to be released at from Broadmoor and move into a clinic closer to Wales, Jennifer died of a sudden and unexplained heart condition. Later, June remarked to their biographer, Marjorie Wallace, that "[Jennifer] gave her life for me and now I have to go on and live for the both of us."

As an identical twin myself, the conundrum that June faces at the grief of losing the person closest in her life and her desire to establish a separate identity has always intrigued me. At times, I've often felt burdened by simply being known as the "older twin" and frequently questioned whether it would be easier if my identity wasn't so firmly rooted in being a twin.

I ask my twin, Salma, to see if she agrees. "We realized we would forever be grouped as 'one' so we decided to go to separate universities to carve out a separate identity rather than a shared one," she tells me.

"When you're forever seen as the same person with the same feelings, attitudes, and emotions, then the thought of being alone doesn't sound outlandish—it's more of an escape."

To see if other twins felt the same, I spoke to 31-year-old identical twins Magda and Jennie Hauptman about their experience. "As teenagers, we struggled to find our individuality," Magda says. "At 15, Jennie and I became night and day because we were forced to dress and do everything alike because it was seen as 'cool' to be twins. We never shared a room as we needed our own space.

"When you're so enmeshed with someone, you can be so close that you get on each other's nerves. I thought about maiming my twin, strangling her, spooning her eyeballs out with a rusty spoon… The list goes on."

While Jennie says the dynamic has shifted as they've got older, saying that "we pretty much rely on each other's support—we will always be co-dependent on each other," it's clear to see that constant comparison and shared identity can become a huge burden.

Alexandria Duval's murder charge was dropped in June after the judge ruled that there was no probable cause to support the charge. But the desperate search for freedom that drives other twins to violent ends may be ultimately futile. As Hauptman puts it: "Think of twins like a marriage, bound for life. Every marriage needs some time apart to survive—but with twins, there's no such thing as divorce."