According to some estimates, 550 women from across Europe have gone to Iraq and Syria to marry IS fighters. Last year at least three young Australian women departed for the front. The authorities have rightly warned that women in radicalised families are at risk of being sent to IS-controlled areas and forced into sex slavery.

But most women go because they're determined to go. Once there, the brides' social media feeds exhibit what Katherine Brown, Defence Studies lecturer at King's College London, describes, with typical British understatement, as "a combination of violence and domesticity that many find jarring". She refers to images posted from Raqqa, Syria, where British women have set up an all-female police brigade. The women carry AK47s, wear suicide belts and hold severed heads. They cook Nutella pancakes, gossip over coffee, do housework and mothering.

For the men, the battlefields of Syria and Iraq are perhaps a kind of Boy's Own adventure with a mediaeval twist. In the caliphate, these young men, no longer castrated by demands for gender equality, can live their ideal of masculinity – raping and decapitating and avenging the faith.

But what of these women, many of them born or at least bred in the West? Like the teenage runaways in the popular imagination, they are still chasing the bad boys. Yet instead of chasing freedom, they're fetishising subjugation; not even for some futuristic cult that promises utopia, but for a religious mania that promises apocalypse.

What did we do wrong with these children? The mother in me can't help asking, even though I refute the implication the West is to blame. Ross Frenett, of the London-based Institute of Strategic Dialogue, says "an awful lot" of extremists, including jihadi brides, are well-adjusted and come from well-off backgrounds. "They are just looking for a sense of belonging." Aren't we all? Brown of King's College says some French jihadi brides cited restrictions on the burqa as their main gripe against home. One Dutch bride bemoaned that Islamic law would never come to Europe. It's not about us, it's about them.