One thing that has always bothered many of the members in our think tank when talking about protecting the American People against international terrorism is that many of the terrorists are not average citizens in their own culture.
Rather, they are highly educated and trained engineers, and that means they understand things like torsion, compression, tension, friction, gravity, explosives, metal fatigue, and in other words they know how to blow things up, as well as how to make them stronger.
An individual with this sort of knowledge knows the weak points of any system and they are trained to find them, and therefore, as terrorists, they will use their mind to exploit those weaknesses.
This is a problem, and it's why we need to be very careful in our engineering circles with those who are less than honorable, or a planning malicious blitzes or destructive acts against humanity.
There was a great article in IEEE Magazine not long ago; "Extremist Engineers - Why Are So Many Jihadis Engineers?" by Susan Karlin, published in September of 2008.
This was indeed, a brilliant article, with lots of examples of engineers who were Islamic Extremists that became terrorists and did a horrific act.
Of the terrorist attacks studied engineers were well over twice as much as the secondary profession of Islamic Studies, which was well over twice as much as the third category of Medicine.
Okay so, this has all been interesting and I've spent 2-days pouring over all the information, and have read enough books on the topic to agree with the findings.
However, one could also say that there are a higher percentage of Engineers, because they are smart enough to pull off larger events which catch the media's attention and become well-known.
Another issue is that if one drops out of engineering school in a Muslim country, they have washed out and may wish to prove their manhood, cunning, intelligence, and wisdom by showing how big of an event they can manage.
Just thinking out loud, I did enjoy researching this topic as others apparently had too.
I also recommend reading; "Terrorist Recruitment and Radicalization in Saudi Arabia" by Thomas Hegghamer.
Please all this.
* Reference;

1. "Anatomy of Egypt's Militant Islamic Groups;" by Diego Gambetta and Steffen Hertog,
2. "Engineers of Jihad," by Hertog, Working Paper Peace Research Institute in Oslo, August 10, 2006.
   
3. "Terrorist Recruitment and Radicalization in Saudi Arabia" by Thomas Hegghamer ** Additional Books Read and Also Recommended by the Author of This Article:
   1. "Marching Towards Hell - America and Islam After Iraq," by Michael Scheuer, Free Press division of Simon and Schuster, New York, NY, 2008, ISBN: 0-7432-9969-8, pp.
      365.
      
   2. "Security - Policing Your Homeland, Your State, Your City," by Howard Safir, St.
      Martin's Press, New York, NY, 2003, ISBN: 0-312-30194-4, pp.
      282.
      
   3. "America the Vulnerable - How Our Government is Failing to Protect Us from Terrorism," by Stephen Flynn, Harper Collins, New York, NY, 2004, ISBN: 0-06-057128-4, pp.
      234.
      
   4. "Thicker Than Oil - America's Uneasy Partnership with Saudi Arabia," Rachel Bronson, Oxford University Press, UK, 2006, ISBN: 0-19-516743-0, pp.
      353.
      
   5. "The U.
      N.
      Exposed - How The United Nations Sabotages America's Security," by Eric Shawn, Sentinel Press division of Penguin Press, New York, NY, 2006, ISBN: 1-595232-020-3, pp.
      318.
      
   6. "Treachery - How America's Friends and Foes are Secretly Arming Our Enemies," by Bill Gertz, Crown Forum division of Random House, New York, NY, 2004, ISBN: 1-4000-5315-3, pp.
      280.