If your friends and family are too skepitcal to spend time investigating 9/11 for themselves, perhaps a simple questions and answers session is the best approach, backed up with links for further reading, often using Wikipedia. I Dedicate this blog to my brother, whose main objection to the idea of a conspiracy is the question concerning the French Newspaper Le Monde.
The Government would never kill their own people, would they? Conspiracies are just a new Internet-fad thing.
A philosopher once wrote:
Those who cannot remember the past are condemned to repeat it