Social Norms
Social Norms are the rules for how people should act in a given group or society. Any behavior that is outside these norms is considered abnormal. For example, if you live in a society where it is common for people to wear plates in their lips, not wearing plates in your lips would be considered outside the social norm. Personality disorders as well as mental and psychological disorders are considered abnormal due to their variance from that which is socially acceptable from the social norms.