I don't want to over do the Kenan Malik quotes, but I think this transcription of a talk he gave is relevant:
RADICALIZATION IS NOT SO SIMPLE
"The real starting point for the making of a homegrown jihadi is not ‘radicalization’ but social disengagement, a sense of estrangement from, resentment of, Western society. It is because they have already rejected mainstream culture, ideas and norms that some Muslims search for an alternative vision of the world. It is not surprising that many wannabe jihadis are either converts to Islam, or Muslims who discovered their faith only relatively late. In both cases, disenchantment with what else is on offer has led them to the black and white moral code that is Islamism. It is not, in other words, a question of being ‘groomed’ or ‘indoctrinated’ but of losing faith in mainstream moral frameworks and searching for an alternative."