Legal Definitions - collateral consanguinity

Collateral consanguinity refers to a blood relationship between individuals who share a common ancestor but do not descend directly from one another. In simpler terms, these individuals are related through a shared family member further up the family tree, but one is not the parent, grandparent, child, or grandchild of the other. They are on "side branches" of the same family tree.

• Example 1: Siblings

  Consider a brother and a sister. They both share the same biological parents. Their parents are their common ancestors. Neither the brother nor the sister is an ancestor of the other (meaning one is not the parent or grandparent of the other), nor is one a descendant of the other (meaning one is not the child or grandchild of the other). They are related on the same generational level, stemming from the same immediate common ancestors.

• Example 2: A great-aunt and her great-nephew

  Imagine a woman and her great-nephew. The great-nephew is the grandson of the woman's brother. Their common ancestors are the woman's parents (who are also the great-nephew's great-grandparents). The great-aunt is not the mother or grandmother of the great-nephew, and the great-nephew is not the son or grandson of the great-aunt. Their relationship branches off from a shared set of great-grandparents, illustrating collateral consanguinity.

• Example 3: Half-siblings

  Two individuals who share only one biological parent (for instance, a brother and sister who have the same mother but different fathers) are half-siblings. Their common ancestor is their shared mother. Neither half-sibling is the parent or child of the other. They are related by blood through their common parent, but they are not in a direct line of descent from each other, perfectly fitting the definition of collateral consanguinity.