As it is with all behavior, it is nothing but natural that certain <em>manuals</em> on how to act before situations are passed along from one generation to another. It is passed to us by our parents and grandparents and whoever else took part in our early-stage education, as it was passed to them by their parents and grandparents, and so on.
These teachings from our early years dwell deep in our unconscious for our whole life, even if we try to deny them (behave differently than how we were taught) because they are passed to us on the same period when our very personality is being formed. This is actually what dictates probably over 90% of how we react before situations on a daily basis. Even though we may choose to act differently than what it says on those '<em>manuals</em>', there's always an urge to act accordingly.
The sense of chivalry and gallantry from men towards women is a great example of these unconscious-driven behaviors application. The feeling of the need to put women on pedestals is so deeply rooted in men's unconscious, that they simply can't help not doing it, because also there is a catch: Since these <em>manuals</em> are given to us in the foundation of our personality, they are what we most rely on when dealing with situations that make us nervous somehow. People tend to act through them on job interviews, when speaking to an audience at a presentation, or when a guy is meeting a girl for the first time.
The best way to 'fight' this urge, and act more freely from these manuals, is through self-reflexion towards self-awareness. Only by better understanding ourselves that we may start acting freely from our old beliefs that limit us.