Are the MAOA and CDH13 genes even real?
Here's the science: according to the Genetics Home Reference the MAOA is an enzyme that breaks down molecules called monoamines.
For all those that failed biology (present) monoamines are chemicals that act as neurotransmitters. You might recognise neurotransmitters called serotonin and dopamine that control mood, emotions and sleep, but there are others as well.
According to the Genetic Literacy Project, CDH13 acts as a signal between cells and has been linked to ADHD, schizophrenia, and bipolar disorder.
What is the connection between MAOA and CDH13, and serial killers?
Apparently, if you have a low functioning MAOA your serotonin struggles to break down. This can lead to "aggressive and violent outbursts".
It is important to note here that while there have been studies to show the connection between MAOA and serial killers - as it seems to be a trend - there is no definitive evidence that it makes you a serial killer, and it's actually more commonly referred to as "the warrior gene".
So, is Betty Cooper a budding serial killer?
TBH, no, probably not.
Betty Cooper turning into a full-blown serial killer might make sense in TV land, but IRL it probs wouldn't be a thing, and this is for a few ~very~ scientific reasons.
While the MAOA increases the likelihood of being aggressive, it certainly doesn't automatically mean you will be homicidal as usually serial killers are triggered by traumatic childhood events.
A lot of studies show that someone becoming a serial killer is "deterministic", and while the Cooper's are BY NO MEANS the perfect family, Betty hasn't exactly experienced the kind of trauma that would usually onset violent tendencies.
On top of that, the gene is usually found in men, and not women.
So even though there are some red flags that usually signal someone has homicidal tendencies, like when Betty killed her cat Cinnamon (after being forced to by her father) or the fact that Betty keeps a diary, like many serial killers, we're 99% sure Betty Cooper isn't a serial killer.