Did a “broken generation” of soldiers returning from World War II spawn America’s so-called “golden age” of serial killers?

That’s the shocking hypothesis put forth by author Peter Vronsky, whose third book, “Sons of Cain: A History of Serial Killers from the Stone Age to the Present,” catalogs 17,000 years of homicidal maniacs, from Cain to Jack the Ripper to the Green River Killer.

While researching his exhaustive history, Vronsky mined for reasons behind the atrocities he was documenting, specifically what was behind the enormous glut of serial killers between 1950 and 2000.

The controversial conclusion he reached to explain the 2,065 butchers who grabbed headlines for spilling blood in the second half of the 20th century: A “hidden surge of war-traumatized fathers” returned home from battlefields in Europe and the Pacific and spawned a generation of murderous emotional cripples.

Vronsky, an investigative historian who also teaches history at Ryerson University in Toronto, recently spoke with The Post about his newest true-crime examination. Some responses have been condensed and edited for clarity.

What’s your theory as to what led to the ‘golden age’ of serial killing?

Well, here’s the problem: We had this dramatic rise of serial homicides starting from roughly the 1970s through the 1980s and ’90s. And we’ve made all sorts of theories about why that is and often we associated this rise with what was happening in the United States at that time: the increased violence of the 1960s and a new kind of hedonism in the 1970s. The problem was that as I wrote about serial killers, I began to understand that they’re formed very early in their life, often as early as 5. It’s a childhood process. So I thought about and realized I needed to back up 20 to 25 years — as the average age for a serial killer when they first kill is 28. And so when I did that and started to look at the birth dates of these so-called “golden age” serial killers, I realized they were all being raised either during the Second World War or immediately after the Second World War in the Cold War period as well. And because the familial is so important in the making of a serial killer, you have to look at the fathers. So what is it that might’ve traumatized the fathers?

And what did you conclude?

So when I began to look at the experience of the G.I. in the Second World War — and when you clear away this notion that this was the last good war and that we fought this horrific enemy but did so nobly — you begin to realize that we couldn’t fight this enemy nobly. We had to fight this enemy with incredible savagery, almost in the way we fought Neanderthals. This was a war of total destruction. And so our young men who went to fight there were called into an almost-genocidal war because we were fighting genocidal perpetrators. Therefore, I think a lot of men came back from that war traumatized and with no outlet for them. When men came back from the Vietnam War, within several years after that, we had diagnosed post-traumatic stress disorder. But nothing of that was available to these men coming back from the Second World War and they had to essentially suck it up — they were tossed the G.I. Bill, told to go to college and forget about it. And so the more I explored the children of World War II veterans, this notion appeared of their fathers returning in this sullen silence from the war and never speaking about it — this kind of brooding shadow — I began to realize that if this is the case with healthy individuals, imagine the fathers of those who became serial killers. We don’t yet have studies, but I hope some graduate student will see this and look at those golden age serial killers. We have so many, so let’s build a database on their fathers: What was their World War II experience? Did they go overseas? Did they see combat?

‘We may have a whole new wave of killers coming from the trauma of families being destroyed by the global financial crisis of 2008.’

What did you find on serial killers from that era who spoke about their fathers?

Their fathers were often veterans coming back from that war in a traumatized state. And then just the horror of it began to emerge in these last two decades when we began to see the rate, for example, of rape that our soldiers perpetrated in that war. The statistics are mind-boggling and we’re talking about rapes of women who we were liberating in France, Italy and so forth. And then when we look at the Pacific — where we really had a genocidal war in terms of a war between races — you see acts of ritualistic necrophilia, the taking of heads, the pulling of teeth and the collection of human trophies and you begin to understand just how traumatic that experience must’ve been. And of course, not only for the guys who are perpetrating these things, but anyone who witnessed or heard about it. I’m sure it was a minority of American soldiers who perpetrated these acts, but a large majority of them must have witnessed it.

What else played a major role in creating the ‘golden age’?

The second stream — and this is one that the FBI has identified as well — was popular true detective and men’s adventure magazines. I remember those magazines as a kid and I remember this visceral feeling I had when seeing those covers. And, of course, those covers were not pornographic, which I think makes it worse because pornography relieves your imagination. You don’t need it anymore. But those true-crime detective and adventure magazines, they called upon you to savor it in your imagination. You had to take it to the next step inside your mind. And so in those magazines, they celebrated the bondage of women, the torture of women in every cover. Each one always had a woman who was bound in a disheveled state, often looking off the cover of the magazine towards the viewer. So it’s almost as if the person who’s looking at the magazine cover is the one who’s about to perpetrate the crime against the figure in the magazine. So it essentially put you in the killer’s mind.

And those magazines were uniquely American?

Distinctly American, yes, that whole pulp era. So if you were a vengeful, traumatized, abused or isolated boy, you probably withdrew into a fantasy world and that world was often about control and revenge. Combine that with puberty and those fantasies of control largely become sexualized. And now you have this imaginary vehicle of how to express those fantasies of control and bondage and rape and murder. So those magazines certainly played a role, along with a kind of familial isolation and the breakdown of the father figure. One thing that’s often missing from the lives of serial killers is the father figure. They often report a dominant mother figure, but either an absent or submissive father. So here you had a generation of traumatized men bringing up children and some of them may be able to deal with their trauma and some may not. But I suspect those who were not able to deal with that ended up traumatizing their own kids either by leaving them, abusing them or just being withdrawn.

Do you expect any blowback from vets over your WWII theory?

I certainly am concerned about it being misinterpreted. There’s only so many things left for us to believe in, and one of the things we believed in was that that was the last “good” war we fought. And so I hope people understand this is not painting a whole generation of veterans. I think veterans know it happened — and it happened to a much greater extent than we were able to articulate. War is not what we see in the movies, especially the Second World War. So I don’t think it’s going to surprise people. Probably the worst of it is over with because certainly those books that came out on the number of incidences of rape that occurred. But it happened and it wasn’t our veterans’ fault. We were fighting an enemy that was far more savage. We were fighting monsters, essentially, and that kind of war required that kind of savagery.

Did your third effort on serial killers satisfy your curiosity?

It satisfied me as to the possibility of explaining why we had this peak in serial killing and why it’s declining today — or why we may have another peak coming if the traumas of the fathers get passed on to their sons. So now we’re looking 20 to 25 years after 2008. And fortunately, not as many men and women had to fight in the War on Terror. It was a limited war and I’m sure it was as brutal as the Second World War, but I’m hoping that simply because of the number of troops deployed that it’s not going to leave the same kind of trace — if my theory is correct — that the Second World War left. But you know, life is becoming more traumatic at home; you don’t need to go to war. We’re living in strange times.

So can we expect another serial killing surge around 2030?

Yes, and certainly that crash of 2008, sure, that changed a lot of families around the world. It destroyed families in a way that we still don’t appreciate or have been able to accurately measure. So when we start talking to those serial killers, the stories we might hear is: “We were living as a family in a home and come 2008, my dad committed suicide. My dad lost his job. He became a drug addict. He was an alcoholic. He was never the same. He lost his pride and I lost my dad.” That may be the emerging narrative.