Inferiority complex can result from three different causes: physical causes, socio-economic causes and immigration.

Physical causes

Inferiority complex resulting from physical causes is mainly because the person in question is either too short (also called the Napoleon complex), or overweight. Because of their unusual physical conditions, such people tend to consider themselves less important than other people. While some people consciously do this, many subconsciously think and behave this way. An example can be two colleagues who work in equal ranks in a company, and who are equally successful in their jobs. When their boss wants to promote one of them to a higher position, the one who is overweight (or shorter, or whatever his/her physical condition is) will tend to think that his/her colleague deserves the promotion and asserts that he simply is not as good as the colleague. As a consequence, this person will start to blame himself for not performing well in his job (even if he does work well), and will try to work harder to compensate for his lack of confidence. Which is usually obvious.

Socio-economic causes

Another common cause of inferiority complex is coming from a lower or lower-middle socio-economic class. This could occur in people, who work for higher-class families or who are often exposed to the lives of higher-class people in daily life. Seeing other people living in higher standards, the person starts to blame himself for not being able to provide his family the same comfort of life. Not only the person feels inferior to higher economic-class people, but a feeling of anger is also usually attached. As a consequence, whenever this person has the opportunity to hinder activities of other people, s/he will subconsciously unleash the desire to do this.

Immigration

This kind of inferiority complex could occur in people who immigrate to other countries (it could also happen in people who immigrate to another city in the same country). While it is more commonly observed in people who immigrate from a lower-life-standard country to a higher, it is also possible to occur in reverse situations. In the former case, the inferiority complex could manifest itself in one of the two extremes: s/he could either feel an animosity towards the natives, and always hang out with other immigrants (especially from his own country if possible), or he could try to impress the natives as much as possible because of the thought that a lower-life-quality in his country means that he is a lower person. In the former case, the individual, whenever there is an opportunity, boasts about his native country all the time in order to give people the impression that he is as important as the other people around. In the latter case, the person does the opposite: he never likes to mention about his home country, tries to lose his identity, and overimitates the natives' life styles. Whenever he sees other immigrants from his native land, he tries to avoid them. This is because of the thought that spending time with other immigrants will prove him to be a failure in integration to the society of the new country.