Great points on company culture from the Raw Signal group in You don’t have a culture problem, you have a management problem:

Culture handbooks don’t produce culture, people do. The culture you experience in your organization is a rolling average of the last thousand interactions you’ve had. Every piece of feedback, every conflict, every trade-off is culture. Every hiring, promotion, and firing, too. Those interactions come from everywhere, but a disproportionate number will come from your close peers, and your own boss. Culture may be everyone’s job, but some people have a lot of sway on your local average.

They go on to explain what managers can—and should!—do to take ownership of the culture in their organizations.