Strict fathers, and sometimes mothers, often refuse to accept their sons’ fascination with girls, sports and the rest of the modern world—helping to create a situation where they felt isolated in their own homes just as they did as minorities in wider Western society. None of this forces young people into the arms of the jihadis, of course, but it helps to create an environment where radicalization can flourish.

Hate preachers and online terror recruiters are adept at stepping into the void. “These people end up being surrogate dads. So many of the guys, some of whom didn’t want to be on camera, said the same thing. ‘God, they really cared; they would call to see if you got home OK. My Dad never did that,’ one of the guys said,” Khan explained. 

One of the former Islamists featured in the documentary is Alyas Karmani, now an imam in Bradford. He said charismatic radicals sucked him into the world of international jihad. “When someone for the first time starts to understand you, emotionally support you—put that arm around you show compassion and love for you—that’s unbelievably powerful and compelling,” he says in the documentary.