What is the causes of rude behave for human being?

People in general have varying aspects that change from time to time. The answer to this question could take a book to explain and in most cases do. Some people were brought up in surroundings that encouraged this type of behavior while others do it unintentionally. More often than not a person that is being rude either has no idea he/she is being rude or they believe that it is the natural way to communicate to another person that is not superior to them. It's the difference between being passive or aggressive. When dealing with a rude individual you need to look at the issue from all aspects. Sometimes a person could have had a really trying day at school, work, or in life generally speaking. As most people say "you just can't judge a book by its cover." The human behavior is a science in itself for more information on this I would suggest a behavioral analysis book. Proper fields of study would be sociology or psychology.