A cousin chart describes the lineage between two cousins within the same side of a family based on the closest shared ancestor. Also known as a table of consanguinity, cousin charts explain the generations, or degrees of removals, between cousins.
Connections between cousins are typically explained by using terms such as "first cousin" and "second cousin." First cousins are the children of siblings, while second cousins are the children of first cousins, and third cousins are the children of second cousins. Degrees of removal explain from which generation a cousin is from. The term "first cousin once removed" indicates that one cousin's grandparent is the other cousin's great-grandparent. "Second cousin once removed" means that two cousins share the same great-grandmother and great-grandfather.
In the downward direction of a generation, which refers to generations born after the person in question, the degrees of removal are the same. The children of a first cousin are first cousins once removed. Grandchildren of a first cousin are first cousins twice removed, and great-grandchildren of a first cousin are first cousins three times removed.
Other types of cousins include double cousins, which refers to children who are the products of one set of siblings marrying another set of siblings, making them doubly related. Step-cousins are the stepchildren of an individual's aunt or uncle or a step-parent's niece or nephew. A cousin-in-law is the cousin of an individual's spouse or the spouse of one's cousin.