Abnormal Behavior and Deviation from Social Norms: Yes, a long-standing pattern of deviant behavior can be considered abnormal. In psychology, behavior is considered abnormal when it deviates significantly from social or cultural norms. These are usually behavior patterns that are not acceptable in the group or community that an individual belongs to.
Social and Cultural Norms: What is considered ‘normal’ behavior varies across cultures. For example, a society that values aggression might consider an individual's assertive behavior as acceptable, whereas another society that prioritizes cooperation may consider such actions as ‘abnormal’.
Maladaptive Behavior: Many psychologists consider behavior as abnormal when it becomes maladaptive. Maladaptive behaviors negatively impact one’s day to day life. For example, persistent aggression can be considered abnormal if it significantly interferes with a person's relationships, education or workplace.
Example: A person who has a persistent pattern of lying to people to manipulate them, and has had this behavior for a long time, can be considered abnormal. This pattern not only deviates from normal behaviour but is also maladaptive as it damages their relations with others.