Hi [Collegue's Name Here],
Just to give you some published estimates: between 10-15% of the world trade center attacks appear to have been Jewish.
About 12% of the New York city population is Jewish. You can do the rest of the math.
Figures taken from link below.:
People in my community died, lost friends or relatives in the attacks – it really saddens me that there are anti-semites out there who spread lies claiming that somehow Jews knew of the attacks, or even further were somehow behind them. I guess if people want to hate Jews they can always find some type of lie to spread about us (100 years ago it was that we liked drinking Christian baby blood http://en.wikipedia.org/wiki/Blood_libel_against_Jews )
It also hurts that people are willing to believe and repeat these kind of vicious lies without even looking to see if they have any basis in reality.
If someone said [my collegue's ethnic/religious group here] were behind the bombings that occurred last month [in Bangalore] or knew about them and failed to warn anyone, I’d be very careful to check the basis of that claim before believing that your community was responsible and, most definitely before repeating it to others as if it were fact.