What is culture?
If a company were a person, its culture would be the inner dialog, character, personality, values, dreams, and mood of the individual. Culture is hard to define because is not one single thing, but the interaction of many different aspects that are often in competition and balance with each other.
Despite what corporate law says, an organization is not one person, but a set of people and their interactions. Company culture is an overall personality that results from the interactions between its people, and the environment in which employees work. It includes elements such as mission, values, atmosphere, ethics, expectations, mood, goals, politics, morals, rules and policies.
Culture starts at the top and grows at the bottom
I am a believer that company culture is what you allowed it to be. It is shaped at the top, but it forms at the bottom. Leadership can take action to promote change, but the shape the changes take is not always predictable. Developing a company culture is an art more than a science, and like any art, it takes practice and unwavering determination to master.
Departments have their own culture, and engineering is no different. As a developer, you can help shape the engineering culture by taking actions to influence the environment. Every time you interact with people in your team, you are throwing a rock in the company culture pond. The rock hits the water and generates waves that ripple radially, changing the engineering culture first, and the overall company culture next.
If you are supportive of your coworkers, you are making the company a little more favorable to everyone. When you crack a joke and make people laugh, you are making the company a bit more fun. If you are cranky, you are going to make the company more irritable. The more weight your personality and position carries, the more pronounced the effect is going to be.
The ripple effect
Imagine that an intern is cranky and has a heated argument with a co-worker. That interaction is going to generate some friction, but the result is going to be limited and mostly localized to the people who saw it. In contrast, imagine that the CEO has a heated argument with the CTO. That kind of clash is most likely going create big waves; the effect is going to affect the overall morale of the company, and the results are felt in all departments.
That is why the company culture is shaped mostly from the top. The top has the largest rocks and throwing them generates big waves. Since the organization is a pyramid, and the majority of the people are at the bottom, the resulting change forms mostly at the bottom as it affects many people. Big waves generated at the top resonate throughout the ranks, and the more people are affected, the more the culture shifts.