Collateral consanguinity is the relationship between persons who are descendants from the same common ancestor but do not descend or ascend from each other. In other words, they are related by blood but do not descend from each other.
The classic example of collateral consanguinity are cousins who have the same grandparents. Another example is the relationship shared between uncle and nephew.
[Last updated in June of 2021 by the Wex Definitions Team]