Here is an explanation of the English-language conventions for naming family relationships, and some technical facts about ancestry.
Relationship Chart
The best tool for understanding the confusing relationships of cousins is a relationship table. On WikiTree our Relationship Finder will do the work for you — the following is just for illustration.
| Common Ancestor | |||||
  |
parent | grandparent | great grandparent | 2nd great grandparent | 3rd great grandparent |
| parent | sibling | niece or nephew | grandniece or grandnephew | great grandniece or grandnephew | 2nd great grandniece or grandnephew |
| grandparent | niece or nephew | 1st cousin | 1st cousin 1 time removed | 1st cousin 2 times removed | 1st cousin 3 times removed |
| great grandparent | grandniece or grandnephew | 1st cousin 1 time removed | 2nd cousin | 2nd cousin 1 time removed | 2nd cousin 2 times removed |
| 2nd great grandparent | great grandniece or grandnephew | 1st cousin 2 times removed | 2nd cousin 1 time removed | 3rd cousin | 3rd cousin 1 time removed |
| 3rd great grandparent | 2nd great grandniece or grandnephew | 1st cousin 3 times removed | 2nd cousin 2 times removed | 3rd cousin 1 time removed | 4th cousin |
To use this chart, start by determing the first common ancestor between two people. Next you name the relationship between the common ancestor and the first person, and between the common ancestor and the second person. For example, for you and your aunt, the first ancestor that you share is a grandparent to you, and a parent to your aunt.
Follow across the horizontal (x-axis) columns to find the name of the relationship between the common ancestor and the first person. For you, this is a grandparent so it would be the second column.
Follow down the vertical (y-axis) rows to find the name of the relationship between the common ancestor and the second person. For your aunt, this is a parent so it would be the first row.
Where the column and the row intersect is the name of the relationship between the first person and the second person. You already knew your relationship with your aunt, but as you can see, the table tells you that you are her niece or nephew.
Deeper Ancestry
To make it easy to read, the table above only has five generations. WikiTree's Relationship Finder searches ten generations. To go even deeper, this Cousin Relationship Calculator will show 100 or more. The page also has some handy definitions.
Half-Relationships
The table above considers the first common ancestor, singular, not the first common pair of ancestors.
Therefore, it doesn't account for "half-" relationships. For example, if you share a common father with someone they are your sibling. If you don't share the same mother, some would call you have a half-sibling.
Relationships by Marriage
The table above only considers "blood" relationships, not relationships through marriage.
Despite having no common ancestry, the following are still family relationships:
- Spouses, i.e. husbands and wives.
- In-laws, i.e. the family of your spouse.
- Aunts and uncles through marriage.
- Step-children, step-siblings, step-parents, step-grandparents, etc.
Number of Ancestors
You have over two thousand direct ancestors in just ten generations. Here's how the numbers work.
- Two parents (1 mother + 1 father = 2)
- Four grandparents (2 grandmothers + 2 grandfathers = 4)
- Subtotal: Six ancestors in two generations (2 + 4 = 6)
- Eight great-grandparents: (4 great-grandmothers + 4 great-grandfathers = 8)
- Subtotal: 14 ancestors in three generations (2 + 4 + 8 = 14)
- 16 great-great-grandparents
- Subtotal: 30 ancestors in four generations (2 + 4 + 8 + 16 = 30)
- 32 3rd great-grandparents
- Subtotal: 62 ancestors in five generations (2 + 4 + 8 + 16 + 32 = 62)
- 64 4th great-grandparents
- Subtotal: 126 ancestors in six generations (2 + 4 + 8 + 16 + 32 + 64 = 126)
- 128 5th great-grandparents
- Subtotal: 254 ancestors in seven generations (2 + 4 + 8 + 16 + 32 + 64 + 128 = 254)
- 256 6th great-grandparents
- Subtotal: 510 ancestors in eight generations (2 + 4 + 8 + 16 + 32 + 64 + 128 + 256 = 510)
- 512 7th great-grandparents
- Subtotal: 1,022 ancestors in nine generations (2 + 4 + 8 + 16 + 32 + 64 + 128 + 256 + 512 = 1022)
- 1,024 8th great-grandparents
- Subtotal: 2,046 ancestors in ten generations (2 + 4 + 8 + 16 + 32 + 64 + 128 + 512 + 1024 = 2046)
However, you might not actually have two thousand different ancestors in these ten generations. This is due to what is called "pedigree collapse".