Is family-linked terrorism a cultural and genetic phenomenon?

National Public Radio “In Worst Attacks, Terrorists Often Have Fraternal Bonds”

This is an interesting — albeit brief — piece on a recent “pattern” that has emerged in terror attacks: teams of attackers are often composed of blood relatives. As a good scientist I have to point out that there’s a danger here of over-generalizing the meaning of this recent trend, but it is a trend worth analyzing with more just three data points.

This NPR piece rightly discusses the fact that familial bonds — and bonds of group membership in general — make one more likely to become “radicalized” once a person you share a close social bond with becomes “radicalized”. Although we may never fully know the family dynamic that drove the Tsarnaev brothers to bomb the Boston Marathon in 2013, the facts we know clearly point to older brother Tamerlan becoming radicalized and then pulling his younger brother Dzhokhar into both his ideology and terrorist plot. Kin selection has likely left us with biological instincts to come to the aid of our relatives, sometimes even when that aid leads to great harm to others. And there are cultural values that reinforce these obligations to family, “family values” that vary in intensity from one culture to the next.

I appreciated that this NPR piece also discussed the fact that the bonds of friendship can have a similar effect, causing friends to radicalize friends. Now maybe it seems obvious that co-conspirators — whether they are planning a terrorist attack or conspiring to host a fun community barbeque in the park — are going to be friends, but the important question is whether friends can radicalize each other before conspiring together. Again, given the groupish nature of humans, this would not be at all surprising. I am sure that a big part of the law enforcement effort to prevent terrorist attacks centers on understanding the social networks of would-be terrorists.

Ideology is a cultural phenomenon, and what culture people are more likely to assume is strongly impacted by their environment. This means that geography plays a role beyond just proximity in determining the risk that a person will commit an act of terrorism: people from an area that is particularly economically depressed and socially isolated are more likely to become radicalized. That means that the family connections we see could in part have nothing to do with family ties per se: families tend to live in geographical proximity to each other and therefore share environments, environments that could foster radicalization.

What’s not at all entertained in this NPR piece is that the family connection observed in terror attacks could be genetic in nature. Perhaps that possibility was beyond the scope of this short piece, but I wonder whether we are too quick to assume that culture and other environmental factors are the sole drivers of extremely-violent behaviors. Let’s face it: if we were talking about family members who all suffered from schitzophrenia, a different behavioral disorder, we certainly would be asking about the hereditary component of the disorder. So why don’t we entertain the idea that susceptibility to radical ideology has a genetic component?

One reason may be that most people maintain an overly simplistic understanding of how genes and environment impact our behaviors: we tend to simplistically assume that either “nature” or “nurture” drive particular behaviors. Although scientists have long ago abandoned this dichotomy (de Waal 1999), the public still tends to think in terms of genes or environment. In the case of culturally-mediated traits like becoming a terrorist, it is tempting to write genetics out of the picture because ideology is so clearly a function of the cultural environment of the terrorist.

But if siblings are more likely to commit acts of terror together, isn’t it possible that genetics plays a role? Once you realize that genes and environment interact to produce behavior, you stop thinking about whether certain individuals are genetically-programmed to become terrorists and instead confront a more subtle reality: different people may have different genetic propensities to become radicalized and commit acts of terror. Part of that genetic propensity might be a generalized propensity to solve problems via violence; clearly our ancestors varied in their propensity for violence, and having some willingness to fight for what one believed in would have been adaptive in the past. But I am more interested in the question of whether some individuals are more susceptible to radical cultural ideas. I want to know whether some individuals lack “immunity” to ideas that lead to very maladaptive behaviors such as those we see in terrorist attacks.

Culture compels us to do some pretty wacky things, and one of the leading hypotheses for why that might be the case is that certain cultures have evolved to become “mental parasites”. What defines a “mental parasite”? Well, if a cultural idea promotes behaviors that reduce your chances of surviving and reproducing biologically, that cultural idea is parasitizing body in order to promote its own survival. And in the case of terrorists — who frequently end up dying for their ideology — the culture of radical ideas seems to be pretty darn parasitic.

Are we all equally susceptible to mental parasites? Probably not, otherwise the success of terrorists attacks would likely be multiplied far beyond their current effect. Most of us are unlikely to become radicalized, and I would suggest that part of that immunity stems from our genetic predispositions. If I am right, there’s good reason to assume that radical cultures can only survive for so long: if they are more likely to be embraced by individuals with particular genetic susceptibility to mental parasites, these mental parasites are likely to eventually kill off their hosts. The only problem is that culture evolves far more rapidly than genes, which means that new mental parasites are likely to evolve more quickly than they kill off their genetically-susceptible hosts. That means that we are likely to be locked in continual battle against a variety of “cultures of violence”, just as we are locked in a continual battle against our more-rapidly-evolving biological parasites. But knowing the degree to which genetics influence propensity for radicalization would better equip us to culturally immunize members of our society against radicalization.

Obviously yesterday’s attack in San Bernadino, California — whether it gets labeled “terrorism” or not — demonstrates that family groups need not be composed of blood relatives in order to perpetrate collective violence. This suggests that genetics cannot be the whole story, a very safe conclusion to draw. But if you think that genetics play no role in who becomes a terrorist, I ask you this simple question: is anyone off the street equally likely to commit acts of terror if exposed to the right cultural environment? Given how many people share a very similar cultural environment with the small minority of terrorists who periodically emerge, it seems clear that there is a genetic component to radicalization. That genetic component likely has to do with the increased susceptibility of particular individuals to radical cultural ideas.