So-called “home-grown” terrorists such as Syed Farook, who slaughtered 14 people last month in San Bernardino, or Muhammad Abdulaziz, who gunned down five U.S. servicemen in Chattanooga last summer, were both second-generation Muslim-Americans whose parents emigrated to the U.S. Most of the terrorists who attacked Paris in November, killing 130 people with guns and bombs, were…