So if economic inequality didn’t nudge certain Muslims to join ISIS, what did? Benmelech suspects that in addition to the fighters’ personal religious ideology, it might be a country’s level of overall cultural homogeneity that makes Muslims feel like they aren’t welcome. Places like Finland might provide generous welfare benefits for much of the population, but some refugees and immigrants there feel so unwanted that thousands have canceled their asylum applications.198 The majority of Finns, after all,199 say they feel “Islam is fundamentally incompatible with Finnish values and culture.” After Finland saw an increase in the number of refugees from Iraq, roving bands of men calling themselves “Soldiers of Odin” began patrolling the streets looking for men who appear Middle Eastern, under the guise of “keeping our women safe.”200 Feeling alienated in this way, some disaffected, radical Muslims in Finland might have warmed to ISIS’s message of a global Islamic caliphate, one in which Muslims are glorified.

This connection between cultural marginalization and an attraction to terror groups has held up repeatedly in research. ISIS recruits are more likely to be second- or third-generation immigrants, for example, which suggests that they gravitate to the group because they feel uncomfortable in either culture.201 In a 2015 study of first- and second-generation Muslim immigrants in the United States, those who felt alienated from American culture and discriminated against also felt more insignificant. In fact, the more “culturally homeless” they felt, the more the discrimination made them feel insignificant. That insignificance, in turn, was associated with greater attraction to a hypothetical fundamentalist group that “promised belonging” and justified extremism to support its cause.202

And it isn’t just ISIS, of course. Research on other types of political radicals, and even school shooters, suggests many of them are motivated by a desire to punish the groups that excluded them.203 White supremacists often target insecure and lonely-looking teens as potential recruits. Angela King, a former neo-Nazi who now runs a group that helps people disengage from hate groups, has described falling in with some young skinheads after being bullied as a child.204 And bullied kids seem primed to be taken up by such groups: lab experiments on social exclusion—which typically involve college students getting “rejected” by a fake group—have found that exclusion reduces cognitive skills and self-awareness.205