Well, I'm not psychologist, but I'm inclined to believe that the kind of religious zealotry that we've witnessed from Islamic extremists has a whole lot more to do with the environment, than with their parental relationships.
Here's a quote from John Lewis Gaddis that I found quite enlightening:
"The final innovation in the Bush strategy deals with the longer-term issue of removing the causes of terrorism and tyranny. Here, again, the president's thinking parallels an emerging consensus within the academic community. For it's becoming clear now that poverty wasn't what caused a group of middle-class and reasonably well-educated Middle Easterners to fly three airplanes into buildings and another into the ground. It was, rather, resentments growing out of the absence of representative institutions in their own societies, so that the only outlet for political dissidence was religious fanaticism." -- A Grand Strategy of Transformation
Personally, I think the real cure is a Middle East Wide free trade zone.