| Who is it? | Relationship to you | Common Ancestors |
|---|---|---|
| child of your sibling | niece or nephew | your parents |
| child of your first cousin | first cousin once removed | your grandparents |
| child of your second cousin | second cousin once removed | your great grandparents |
| child of your third cousin | third cousin once removed | your great great grandparents |
| child of your n-th cousin for n>3 | n-th cousin once removed | your (n-1) times great grandparents |
Note that we could speak of zeroth cousins instead of siblings. A sibling relationship is exactly the same kind of relationship as is a cousin relationship. It's just that siblings are one generation closer than are first cousins. Similarly, a niece or a nephew is a zeroth cousin once removed.