From the American Prospect on how it's practically impossible to profile homegrown terrorists:
Another study found only broad trends among domestic jihadist terrorists, specifically that they are overwhelmingly male and about two-thirds of them are younger than 30 years old. As the above discussion may suggest, generalizing about the individuals involved is problematic. Indeed, there does not appear to be a common thread connecting the U.S. Army psychiatrist Major Nidal Hasan with the Caucasian convert, Daniel Patrick Boyd; the Afghan immigrant Najibullah Zazi with Carlos Bledsoe, an African American of a happy childhood who converted to Islam and renamed himself Abdulhakim Muhammed; David Headley, who was born Daood Gilani to a successful Pakistani immigrant father and American mother, with Talib Islam, who was born Michael Finton and raised in multiple foster homes; or the educated pharmacist Tarek Mehanna, with the Somali American from Minneapolis Shirwa Ahmed, who traveled to the land of his birth and became the first U.S. citizen suicide bomber.
Yup, not much in common there ... So, let's keep on giving the third degree at the airport to the 86-year-old retired general who tried to sneak his Medal of Honor on his trip to address cadets at West Point.