Relationship Names

This page only covers western-style kinship names, and using the English terms. There are systems which only identify relationships based on gender and generation, as well as those that have a different name for every relative. Western-style names are a combination of the two.

This page also doesn't consider “fictive” kinship, in which an individual is given kinship title that doesn't correspond to an actual biological relationship, but is instead used because the individual is often a close friend. In western culture, aunt and uncle are commonly used for such relationships.

Basic Relationships

Determining the naming relationship between any two people who descend from a common ancestor is pretty easy. (The social relationships, if any, are a different matter.) While the table below will show up to third cousins, it is followed by a few rules that will work for any number of generations.

There are three classes of relationships (colors correspond to areas of the table below). Note that the common ancestor is expected to be the most closely related common ancestor. Also, the complexities of double, triple, and quadruple cousins is not included. (See the sections below the table for an explanation of these.)

Relationship Table

The numbers represent the number of generations the person is from the common ancestor. So, to find a relationhip between person A and person B:

  1. determine the number of generations that person A is removed from the common ancestor and locate that number down the left column;
  2. determine the number of generations that person B is removed from the common ancestor and locate that number along the top row;
  3. the relationship name is where this row and column meet.

For example, if A is 3 generations and B is 1, their relationship is, "Person A is the great niece or nephew of person B."

0 1 2 3 4
0 common ancestor parent grandparent great grandparent great great grandparent
1 child sibling aunt/uncle great aunt/uncle great great aunt/uncle
2 grandchild niece/nephew first cousin first cousin
once removed
first cousin
twice removed
3 great grandchild great niece/nephew first cousin
once removed
second cousin second cousin
once removed
4 great great grandchild great great niece/nephew first cousin
twice removed
second cousin
once removed
third cousin

Rules for Naming Any Relationship

A generalized method for determining the names given to these relationships is defined by the following rules. The trivial case of "self" is not included here.

  1. Determine the number of generations each person is from the most recent common ancestor, and call these their generation numbers.

    Example: A child of the common ancestor is generation 1, a grandchild is generation 2, etc. (The common ancestor is generation 0.)
  2. If one of the persons is the common ancestor, the other is a child (generation 1), grandchild (generation 2), great grandchild (generation 3), etc. The number of “great” qualifiers to use is 2 less than the generation number of the person. (And is obviously not used for generation 1 or 2.) (Change "child" to "parent" for identifying the relationship in the other direction.)
  3. If one of the persons is a child of the common ancestor, the other is a sibling (generation 1), niece or nephew (generation 2), great niece or nephew (generation 3), great great niece or nephew (generation 4), etc. The number of “great” qualifiers added for generations after nephew or niece is 2 less than the generation. (Change "niece/nephew" to "aunt/uncle" for identifying the relationship in the other direction.)
  4. If both persons are more than 1 generation from the common ancestor and are the same generation number, they are simple cousins. The level of cousin is one less than the generation number.

    Example: If both persons are grandchildren (generation 2) of the common ancestor, they are first cousins.
  5. If both persons are more than 1 generation from the common ancestor and have different generation numbers, they are cousins “removed.” The level of cousin is 1 less than the smaller generation, and the number of times removed is the difference between the generations.

    Example: If one individual is a grandchild (generation 2) and the other is a great grandchild (generation 3), they are first cousins, once removed.

Double, Triple, and Quadruple Cousins

The term “consanguinity” is used to define a measure of the closeness of the relationship between two individuals.

When two or more siblings from one family marry siblings from one other family, the children of those families are known as “double first cousins” and have a higher degree of consanguinity than normal cousins. This is because they share both sets of grandparents. (This relationship is not shown in the table above.) A double cousin is also know by the term “cousins on both sides.”

Things become more significant when one set of siblings are identical (twins, triplets, etc.) or both sets are identical. The first case are known as triple first cousins, the latter as quadruple first cousins. Genetically, quadruple first cousins are indistinguishable from full siblings.