Final answer:
A caste system is a form of social stratification based on ascribed status, which individuals cannot change because it is determined by their birth into a specific social group.
Step-by-step explanation:
The factor being described in the question is caste, a system of social stratification based on ascribed status. In a caste system, individuals are born into a social group from which they cannot move out, which is largely influenced by factors such as familial lineage and hereditary characteristics. This stands in contrast to systems where status can be achieved through personal efforts and accomplishments. The sociological concept of status differentiates between ascribed statuses, which are those conditions individuals are born into, like caste, and achieved statuses, like being a college graduate, that can be obtained through personal effort.
Caste systems have historically relegated people to specific societal roles and often imposed restrictions on social interaction and mobility between the groups. Examples of caste systems can be seen in various parts of the world, such as the traditional social stratification in India, or as argued by sociologists, in the form of a racial caste system in the United States. The inevitability of one's social group in a caste system underscores the inflexibility and inherent inequality of ascribed statuses.