‘Riverdale’: Betty’s “Serial Killer Gene” Is a Real Thing… Sort Of

For three seasons, Riverdale‘s Betty Cooper (Lili Reinhart) has struggled with the dark side of her nature. From nearly murdering a fellow student in a hot tub in Season 1, to being groomed to follow in her serial killer father’s footsteps in Season 2, Betty has been grappling with the idea that she might be more bad than good. That all came to a head last night (May 8) on “Chapter Fifty-Six: The Dark Secret of Harvest House,” when a surprising revelation from her mother Alice Cooper (Mädchen Amick) gave a scientific explanation for Betty’s darkness… Though there’s a few asterisks on this particular piece of information.

Spoilers for Riverdale “Chapter Fifty-Six: The Dark Secret of Harvest House” past this point.

In the episode, Betty has joined The Farm, a cult run by the enigmatic Edgar Evernever (Chad Michael Murray). Part of their whole thing is radical honesty, which in this case means sitting Betty down with Alice, and her sister Polly (Tiera Skovbye) and finding out that she has what Polly calls “the serial killer genes.” According to Alice, when Betty was eight years old, she fell off her bike. They took her to the hospital for her concussion, and while she was there for an extended stay the doctors did some real quick genetic testing (a totally normal thing to do for someone with a concussion), and discovered that Betty has the MAOA and CDH13 genes. Polly elaborates that the rest of the family was tested, and nobody else has those genes — including Hal Cooper (Lochlyn Munro), who is a legit, confirmed serial killer.

“You have a predisposition to violence,” Polly tells the shocked Betty, who doesn’t quite believe them but follows along anyway.

Forgetting the idea of whether Edgar and the Coopers are lying to Betty — and given later in the episode it turns out Polly is masquerading as Betty after they think she’s been hypnotized by Edgar, so it’s a fair bet they’re not telling the truth, or the whole truth — is the serial killer gene a real thing?

Well, sort of.

Back in the ’90s, there was a bunch of research into the origins of violent behavior, and at least one of those studies focused on something called the “warrior gene.” This so-called warrior gene secretes an enzyme named monoamine oxidase A (or MAOA), which may or may not affect the brain’s release of dopamine and serotonin. Though this is the simplified version, if these aren’t released correctly, your brain doesn’t get the proper flight or fight response, leading to (again, potentially) anger and possibly even violence.

Further study into the gene showed that it wasn’t necessarily MAOA that linked to this behavior, it was an aberrant form of the gene, specifically an allele called MAOA-L. And in fact, nearly every time MAOA-L showed up, it was on the X chromosome. What that means is that having a second, correctly coded X chromosome (a.k.a., if you are female) could suppress the negative effects of the defective X chromosome, so behavior only really manifests itself, and even then rarely, in males (who have a Y chromosome and therefore can not provide a back-up, correctly coded gene). If you want a good, longer rundown, you can check out this blog on Scientific American.

CDH13 has been studied significantly fewer times than MAOA, and the science is even more suspect. Though it has been linked to everything from schizophrenia to bipolar disorder, the defective form of the gene (a correctly coded CDH13 doesn’t show any negative side effects) hasn’t popped up with enough consistency to form any conclusions about it factoring into people turning out to be serial killers.

In fact, both MAOA and CDH13 are very much on the cusp of pseudoscience, more along the lines of correlation than causation. Have defective MAOA genes been discovered in serial killers? Yes. Has every serial killer had a defective MAOA gene? No.

Making matters worse, the “warrior gene” has repeatedly been used for racist research, to prove that a specific group of humans are more violent, because they all have this gene; usually for extremely suspect or biased reasons. Specifically, a study in the early 2000s in New Zealand “proved” that Maori men were “more violent” than other New Zealdaners because of MAOA. A similar study said the same thing about African-American males versus white males. See the pattern there? It’s not too hidden, and these sorts of studies only cast more doubt on the overall “science” of the warrior gene.

How does this tie back to Betty, and Riverdale? First of all, as usual, the show skirts real world issues by skipping any actual scientific explanations. It’s fantasy, essentially, and I’d doubt at any point someone will explain what I laid out above. In the world of Riverdale, MAOA and CDH13 are the serial killer genes. Good. Fine. But even if Betty has them, as proven in the show by the fact that Hal, a serial killer, doesn’t have them, again correlation does not equal causation. Betty could even have two defective X chromosomes with matching MAOA-L, and still not be a serial killer. That’s just not how it works, despite what Polly wants her to believe.

The main lesson, though? Be careful when you’re riding your bike.

Riverdale airs Wednesdays at 8/7c on The CW

Where to stream Riverdale