Can a company manufacture a tribe? No, but you can support or hinder its growth. In Escape form Cubicle Nation, Pamela Slim writes "Don’t spend millions of dollars to try and change your culture. Corporate culture is a natural thing that cannot be manufactured. No amount of posters, incentive programs, PowerPoint presentations or slogans on websites will affect the hearts and minds of your employees. If you want to see things change immediately, stop acting like an a____e [edited from book original for younger viewers]. If you see one of your senior managers acting like an a____e, ask him to stop. If he doesn’t stop, fire him. You will be amazed at how fast the culture shifts."
I like this approach. Weeding out a few a___e from your organization can do wonders.