Ascertaining Generational Relationships

Kinship Terminology

Cousins

A first cousin is the child of your aunt and uncle (your aunt or uncle is a sibling to one of your parents). If your cousin has a child, that child is a first cousin once removed to you, i.e. one generation removed from being a first cousin. If you have a child, your child is a second cousin to your first cousin's child. If your first cousin has a grandchild, that grandchild is a first cousin twice removed to you, and a third cousin to your grandchild.

PARENT
Child	Sibling	Child
Grandchild	Cousin	Grandchild
Great-grandchild	Second cousin	Great-grandchild
Second great-grandchild	Third cousin	Second great-grandchild
Third great-grandchild	Fourth cousin	Third great-grandchild
Fourth great-grandchild	Fifth cousin	Fourth great-grandchild
Fifth great-grandchild	Sixth cousin	Fifth great-grandchild

The great-grandchild on the left (above) is a second cousin twice removed to the third great-grandchild on the right (above). Please note that the third great-grandchild on the right is not a fourth cousin twice removed to the great-grandchild on the left; the relationship is still second cousin twice removed.

Accordingly:

1. first cousins always share a grandparent
2. second cousins always share a great-grandparent
3. third cousins always share a second great-grandparent
4. fourth cousins always share a third great-grandparent
5. fifth cousins always share a fourth great-grandparent

So the Cousin rule-of-thumb is that the greats are always one less than the cousin relationship.

The above method of determining relationship is:

• the legal one used by all courts in the USA
• the accepted one used by genealogists

An alternative method refers to a first cousin once removed as a second cousin; a first cousin twice removed as a third cousin; a first cousin three times removed as a fourth cousin, and so on. This is likely why there is so much confusion on the issue of cousins and removed.

Half-Cousins

The word half means only one of two parents is the blood parent, so where two siblings share only one parent, they are half-siblings. The children of these two half-siblings would be half-cousins, because they share only one of the grandparents.

So, half-cousins are called that, because they share only one of the two grandparents commonly. As far as half-cousin and removed is concerned, the same rules apply as to full cousins.

Double-Cousins

Double cousins are the result of marriages between two brothers and two sisters (of another family). The children of each married pair are cousins to each other, not only by way of their father's family, but by way of their mother's family as well. Otherwise, the same rules apply as to full cousins; so one (whose grandparents were brothers who married sisters) could have a second double cousin once removed.

A Chart for Determining Relationships
	0	1	2	3	4	5	6	7	8
0	CA	C	GC	GGC	2GGC	3GGC	4GGC	5GGC	6GGC
1	C	S	N	GN	GGN	2GGN	3GGN	4GGN	5GGN
2	GC	N	1C	1C1R	1C2R	1C3R	1C4R	1C5R	1C6R
3	GGC	GN	1C1R	2C	2C1R	2C2R	2C3R	2C4R	2C5R
4	2GGC	GGN	1C2R	2C1R	3C	3C1R	3C2R	3C3R	3C4R
5	3GGC	2GGN	1C3R	2C2R	3C1R	4C	4C1R	4C2R	4C3R
6	4GGC	3GGN	1C4R	2C3R	3C2R	4C1R	5C	5C1R	5C2R
7	5GGC	4GGN	1C5R	2C4R	3C3R	4C2R	5C1R	6C	6C1R
8	6GGC	5GGN	1C6R	2C5R	3C4R	4C3R	5C2R	6C1R	7C

On the top row, find the relationship of one person to the common ancestor and follow the column straight down. Find the other person's relationship to the common ancestor on the left hand column and follow that row straight across. The relationship is where the projected row and column meet.

CA	Common Ancestor
C	Child
S	Sibling
GC	Grandchild
GGC	Great-grandchild
N	Niece/Nephew
GN	Grand-niece/nephew
GGN	Great-great-niece/nephew
#C	Number of cousin (1C=1st cousin, 2C=2nd cousin, etc.)
#R	Number of times removed (1R=once removed, 2R=twice removed, etc.)

NOTE: A first cousin once removed is a term that could describe either the child of your first cousin (in the descendancy) or the child of your great-aunt (in the ascendancy).

					great great great grandparent
				great great grandparent		great great granduncle grandaunt
			great grandparent		great granduncle grandaunt		1st cousin thrice removed
		grandparent		granduncle grandaunt		1st cousin twice removed		2nd cousin twice removed
	parent		uncle aunt		1st cousin once removed		2nd cousin once removed		3rd cousin once removed
SELF		brother sister		1st cousin		2nd cousin		3rd cousin		4th cousin
son daughter			nephew niece		1st cousin once removed		2nd cousin once removed		3rd cousin once removed
grandson granddaughter				grandnephew grandniece		1st cousin twice removed		2nd cousin twice removed		3rd cousin twice removed

great great great grandparent	great great great granduncle grandaunt	1st cousin five times removed	2nd cousin five times removed	3rd cousin five times removed	4th cousin five times removed
great great grandparent	great great granduncle grandaunt	1st cousin four times removed	2nd cousin four times removed	3rd cousin four times removed	4th cousin four times removed
great grandparent	great granduncle grandaunt	1st cousin thrice removed	2nd cousin thrice removed	3rd cousin thrice removed	4th cousin thrice removed
grandparent	granduncle grandaunt	1st cousin twice removed	2nd cousin twice removed	3rd cousin twice removed	4th cousin twice removed
parent	uncle aunt	1st cousin once removed	2nd cousin once removed	3rd cousin once removed	4th cousin once removed
SELF	brother sister	1st cousin	2nd cousin	3rd cousin	4th cousin
son daughter	nephew niece	1st cousin once removed	2nd cousin once removed	3rd cousin once removed	4th cousin once removed
grandson granddaughter	grandnephew grandniece	1st cousin twice removed	2nd cousin twice removed	3rd cousin twice removed	4th cousin twice removed