A more thorough explanation:

Collateral consanguinity

Collateral consanguinity refers to the blood relationship between people who share a common ancestor but are not directly descended from each other. This means that they are related by blood, but not in a direct line of descent. A common example of collateral consanguinity is the relationship between cousins who share the same grandparents. Another example is the relationship between an uncle and a nephew.

• Cousins who share the same grandparents
• Uncle and nephew

For example, if two people have the same grandparents, they are cousins and share collateral consanguinity. They are related by blood, but not in a direct line of descent. Similarly, an uncle and nephew share collateral consanguinity because they are both descended from the same common ancestor, but the nephew is not directly descended from the uncle.