"Research published in The Journal of Aggression and Violent Behaviour has proven a connection between suicide bombers and depression and physical handicaps (BT, December 15th 2010 “Why most terrorists are useless”). Research suggests that many suicide bombers are suffering from depression, and their actions are just a socially accepted (among Muslims) way of committing suicide in order to end their mental torment."
People with low intelligence (because of inbreeding) might also be easier to brainwash with fundamentalist Islam.