Culture has a very great influence on who you are. Yet, it is mostly invisible to you as we are not exposed to other cultures too much to see how they are different. In general, culture is an arbitrary set of rules.
Just a couple of examples:
A British boss asked a new, young American employee if he would like to have an early lunch at 11 am each day. The employee said ‘Yeah, that would be great!’ The boss immediately said “With that kind of attitude, you may as well forget about lunch!” The employee and the boss were both baffled by what went wrong. [In England, saying “yeah” in that context is seen as rude and disrespectful.]
A Japanese businessman wants to tell his Norwegian client that he is uninterested in a particular sale. So he says “That will be very difficult.” The Norwegian eagerly asks how he can help. The Japanese is mystified. To him, saying that something is difficult is a polite way of saying “No way in hell!“. Dave Barry tells the story of being on a trip to Japan and working with a Japanese airline clerk on taking a flight from one city to another. On being asked about it, the clerk said “Perhaps you would prefer to take the train.” So he said “NO, I want to fly.” So she said “There are many other ways to go.” He said “yes, but I think it would be best to fly.” She said “It would very difficult”. Eventually, it came out that there were no flights between those cities.