# What are first/second/third cousins?

Once I was told that

I am the second cousin of my uncle's son?

Where the number before cousin doesn't depict the number of cousins, but rather it tells how close of a relation you are in with the person.

But how does this works out? What would be my real brother be to me if the relation is evaluated using the above method. And how many cousins could exist like that? can there be fourth/fifth...eighth cousin also?

• There's actually a calculator on Wolfram Alpha that explains relationships diagrammatically. You can query for a title, e.g. "second cousin", or you can give the relationship "mother's sister's daughter's son". And if you want you can find out the relationship between Lone Star and Dark Helmet. :-) Commented Aug 25, 2019 at 4:44
• @HostileFork -- Your comment could be the start of a good answer. Commented Aug 25, 2019 at 5:38
• @HostileFork -- Unfortunately, Wolfram Alpha does not correctly interpret "zeroeth cousin". It does not go lower than "first cousin". Commented Aug 25, 2019 at 5:54

The example sentence is grammatically correct. Unfortunately, if "uncle" has its primary meaning, the sentence is semantically incorrect. You are actually the first cousin of your uncle's son. And if you extrapolate the "cousin" relationship, your brother is your "zeroeth cousin". (But nobody says "zeroeth cousin".) You can extrapolate the "cousin" relationship in the other direction as far as you want, to as remote a kinship as you can find a genealogy for.

The following family tree has no half-brothers and no half-sisters:

``````Paternal         Paternal            Maternal        Maternal
grandfather ===  grandmother         grandfather === grandmother
|                                   |
--------------------------          -------------------------
|           |            |          |           |           |
Aunt       Uncle        Father === Mother       Aunt       Uncle === Aunt
|                                 |
-----------------------                      |
Brother        |          |          |        Sister      First
in-law  === Sister      Self      Brother === in-law      cousin === In-law
|                                 |                      |
------------                      ------------           First cousin
|          |                      |          |            once removed === In-law
Niece      Nephew                  Niece      Nephew                       |
First cousin
twice removed
``````

Some of these terms are gendered:

``````Generation    Male relatives    Female relatives    Gender-neutral term
----------    --------------    ----------------    -------------------
Grandfather       Grandmother         Grandparent
Great-uncle       Great-aunt
Previous     Father            Mother              Parent
Previous     Uncle             Aunt
Same                                               Self
Same         Brother           Sister              Sibling
Same         Husband           Wife                Spouse
Next         Son               Daughter            Child
Next         Nephew            Niece
Grandson          Granddaughter       Grandchild
``````

"Uncle" has three common meanings:

• One's father's brother or one's mother's brother (this is the primary meaning).
• A male relative in an older generation who is not one's direct ancestor (this is a generalization)
• A man, who is a friend of the family, who is introduced to the children as "Uncle <so-and-so>". (this is a further generalization)

Also:

• Siblings share parents.
• First cousins share grandparents.
• Second cousins share great-grandparents.
• Third cousins share great-great grandparents.
• et cetera.

If there are extra generations on one side of the family tree, but not on the other, the relationship is described by finding the level at which there are the same number of generations, and then providing a modifier.

• If the level at which there are the same number of generations is zero, the relationship is described by adding "grand" and "great" to a nuclear family relationship. For example:

• Father/son
• Grandfather/grandson
• Great-grandfather/great-grandson
• Great-great-grandfather/great-geat-grandson
• et cetera
• If the level at which there are the same number of generations is one, the relationship is described by adding "grand" and "great" to an aunt-or-uncle/niece-or-nephew family relationship. For example:

• Aunt/niece
• Great-aunt/grandniece
• Great-great-aunt/great-grandniece
• et cetera
• If the level at which there are the same number of generations is more than one, the relationship is described by adding "<number of times> removed" to the cousin relationship. The same terms are used for both directions of the relationship. For example:

• The language does not impose an upper limit on the number before "cousin", nor on the number before "removed". If your family has long generations, and a related family has short generations, you might have an eighth cousin five-times removed.

Once I was told that I am the second cousin of my uncle's son?

Where the number before cousin doesn't depict the number of cousins, but rather it tells how close of a relation you are in with the person.

But how does this works out? What would be my real brother be to me if the relation is evaluated using the above method. And how many cousins could exist like that? can there be fourth/fifth...eighth cousin also?

Firstly you are miss-informed

Your Uncles son is your cousin (1ST cousin) not your second cousin (Unless he is not a real uncle).

Secondly only cousins are referred to like this not Brothers.

Thirdly The relationship is easy to relate