Kinship Names

This page only covers English (western-style) kinship names between two individuals, based on descent from a common ancestor — an ancestor to both individuals. Note that this common ancestor may be one of those individuals.

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

Note that English-language kinship include words that may or may not indicate gender. Specifically, father/mother, son/daughter, brother/sister, uncle/aunt, and nephew/niece all represent (male/female) gender, while parent, child, sibling, and cousin do not. There are no genderless English words for uncle/aunt and nephew/niece, though some may become common over the course of the next few years, due to the gradual acceptance of non-binary naming conventions.

For simplicity, the table below uses the genderless forms, when possible.

Relationship Table

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. The complexities of double, triple, and quadruple cousins are not included in this table, but are described below.

The numbers represent the number of generations the person is from their closest common ancestor. Remember that the relationship of the common ancestor to themselves would be "self" and be 0 generations. So, to find a relationship 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	2nd-great grandparent
1	child	sibling	aunt/uncle	great aunt/uncle	2nd-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	2nd-great grandchild	2nd-great niece/nephew	first cousin twice removed	second cousin once removed	third cousin

In short,

• If person A is the common ancestor, person B is a direct descendant (child, grandchild, etc.) of person A. Conversely, person A is the parent, grandparent, etc. of person B.
• If person A is a child of the common ancestor, person B is a sibling, niece, or nephew of person A. (Conversely, person A is a sibling, aunt or uncle of person B.)
• In any other case, the persons are cousins. If these cousins are different numbers of generations from the common ancestor, they are cousins “removed”.

General Rules (Including "Removed")

A general method for determining the names given to kinship relationships is given here.

1. Determine the number of generations each person is from their closest common ancestor, and call these their generation numbers.
   
   Example: The common ancestor, or "self," is generation 0. A child of the common ancestor is generation 1, a grandchild is generation 2, etc.
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 (and is 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 number (and is not used for generation 1 or 2). 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 another 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. The phrase “cousins on both sides” is also used for double cousins.

Things become more significant when one or both sets of siblings are identical (twins, triplets, etc.). When only one set of siblings is identical, two individuals who are not siblings are triple first cousins. When both sets are identical, non-siblings are quadruple first cousins. Genetically, quadruple first cousins are indistinguishable from full siblings.