Riverdale's "The Pincushion Man" finally revealed what the heck Betty's pseudo boyfriend Glen Scot's deal was, and honestly, it was relatively surprising. No, it doesn't seem like Glen is the Trash Bag Killer, or even the person holding Betty's sister Polly captive. Instead, Glen is trash in a different way: His romance with Betty was seemingly all so he could write a dissertation on her family, which, as he puts it, is the perfect case study in nature vs. nurture. Despite the fact that Betty's family boasts many murderers, only a few actually have the serial killer gene on Riverdale.

What is the serial killer gene? Well, it's actually a real thing — kinda. The monoamine oxidase A (MAOA) gene is real, and a low-functioning MAOA has linked to increased levels of aggression and violence. It's sometimes referred to as the "warrior gene."

Of course, Riverdale isn't exactly interested in the nuances of genomics. Instead, the presence of the "serial killer gene" has hung over the Cooper family's head for years, because some family members have it — and others, well, are killers despite the fact that it's not present in their DNA.

So who has the serial killer gene? Here's a rundown.

Hal Cooper

You would think that the Black Hood — who was killed by Penelope Blossom in Season 3 after terrorizing Riverdale with his murder spree — would absolutely have the serial killer gene. His whole identity was built on being a serial killer. Alas, as Polly tells Betty during her time at the farm, Hal doesn't have the serial killer gene. This is particularly odd given that his dad was also a murderer known as the Riverdale Reaper, however, it does work with Glen's theory that while some murderers are born, others are made — Hal's parents definitely indoctrinated him into the whole murder thing. Remember that creepy video tape?!