Everyone has stereotypes; most often they have to do with people. Stereotypes are learned as a result of experience or in childhood from parents, teachers, and the surrounding social environment.
Stereotypes arise from human anxiety or fear about the unknown, untried new experiences or situations. People become anxious when they do not know what is expected of them or what to expect from other people. To reduce personal anxiety, a person will take any experience they have had before, or take someone else's experience, and project that knowledge into a new situation, then react in a way they think is appropriate. Being armed with this so-called knowledge (stereotype) , they are not afraid of a new situation with new people.
Stereotyping is dangerous because instead of reacting or behaving naturally in a situation, the individual will react or behave according the stereotype which can lead to discrimination.
Stereotyping can impact our performance of duties. Male and female supervisors, and male and female employees or military personnel who act according to sex role stereotypes can interfere with the proper assignment and accomplishment of work.
Example: A woman was not selected for a job because the boss felt women are not aggressive enough.