Understanding First, Second, and Cousins Once Removed

A mathematical and linguistic guide explaining degrees of collateral kinship, common ancestors, and generational differences.

First cousins share grandparents. Second cousins share great-grandparents. Third cousins share great-great-grandparents. The term 'removed' refers to generational asymmetry: a first cousin once removed is either the child of your first cousin, or the first cousin of your parent. Understanding this generational coordinate eliminates common genealogical confusion.