From The Art and Popular Culture Encyclopedia
In kinship terminology, a cousin is a relative with whom one shares a common ancestor (or ancestors). In modern usage, the term is rarely used when referring to a relative in one's immediate family where there is a more specific term to describe the relationship (e.g. one's parents, siblings and descendants). The term blood relative can be used synonymously, and underlines the existence of a genetic link. A system of "degrees" and "removals" is used to describe the relationship between the two cousins and the ancestor they have in common.
The degree (first, second, third cousin, etc.) indicates one less than the minimum number of generations between both cousins and the nearest common ancestor. For example, a person with whom one shares a grandparent (but not a parent) is a first cousin; someone with whom one shares a great-grandparent (but not a grandparent or a parent) is a second cousin; and someone with whom one shares a great-great-grandparent (but not a great-grandparent or grandparent or parent) is a third cousin; and so on.
The removal (once removed, twice removed, etc.) indicates the number of generations, if any, separating the two cousins from each other. The child of one's first cousin is one's "first cousin once removed" because the one generation separation represents one "removal". Oneself and the child are still considered first cousins, as one's grandparent (this child's great-grandparent), as the most recent common ancestor, represents one "degree".
Non-genealogical usage often eliminates the degrees and removals, and refers to people with common ancestors merely as "cousins" or "distant cousins". Alternatively, the terms second cousin and first cousin once removed are often incorrectly used interchangeably.
The system can handle kinships going back any number of generations (subject to the genealogical information being available).
- Collateral descendant
- Cousin marriage
- Cross cousin
- Genealogical numbering systems
- Kinship terminology
- List of coupled cousins
- Most recent common ancestor
- Parallel cousin