The History and Continuing Legacy of id is the name of an article published by The Game of the Moment. The piece features lots of quotes from past and current id employees, including this one from John Carmack regarding the Clan scene:

"It was so odd the way it happened -- internally, we had talked of clans of warriors before the game was released, but I don't think we ever publicly talked about it, and to have the same terminology apparently spontaneously evolve in the user community was pretty weird. I love it."