You start letting women into your group the guys start losing interest in talking tech. It's extremely viral - just one or two is enough, three and tech talk will fade out in a matter of weeks.
My advice - if you have a tech discussion group, find some women. Volunteers are best, but I know some of you techies out there will have to pay - but it's still worth it.
Of course this is a little hard on those who think logic has important meaning, but hey, they brought it on themselves.