A double first cousin is a specific type of cousin relationship that occurs when two siblings from one family have children with two siblings from another family. In simpler terms, double first cousins share both sets of grandparents, making them closer relatives than regular first cousins.
To break it down further:
Regular First Cousins: First cousins are the children of your parent’s siblings. For example, if your mother has a brother, his children are your first cousins.
Double First Cousins: This situation arises when:
- Your mother has a sister (let’s call her Aunt A), and Aunt A has children (your first cousins).
- At the same time, your mother also has a brother (let’s call him Uncle B), and Uncle B has children with Aunt A’s sister (let’s call her Aunt C).
In this case, the children of Aunt A (your first cousins) and the children of Uncle B (who is your parent) are double first cousins because they share both sets of grandparents.
Double first cousins are genetically closer than regular first cousins because they share a greater proportion of their ancestry. In terms of genetics, double first cousins share about 25% of their DNA, compared to the roughly 12.5% shared by regular first cousins. This closer genetic relationship can have implications in terms of family health history and genetics.