UK police officer’s son is waging jihad in the Islamic State

Insane Britannia: shoes are no good to send to his jihadi brother but underwear or socks would have been OK. But the main point of interest in this story is not with Majdi Shajira at all, but with his brother Amer. Presumably the household in which he was raised, since his father was a police officer, was “moderate.” How did he come to misunderstand his peaceful, moderate religion?