What is a Third Cousin and how are they related to me?
When it comes to family relationships, the term "cousin" can refer to a wide range of relationships with varying degrees of genetic relatedness. One such relationship is that of a third cousin, which describes a cousin who is more distantly related than a first or second cousin.
A third cousin is the child of one's parent's second cousin, or the second cousin of one's own grandparent. In other words, a third cousin shares a set of great-great-grandparents with you. This means that they share about 0.78% of their DNA with you, as you can see on this handy chart at ISOGG.
To give an example, let's say that your great-grandfather had a sibling who had a child. That child would be your second cousin, once removed. If that child had a child, that child would be your third cousin. Alternatively, if your great-great-grandparents had a child who had a child, and that child had a child, that child would also be your third cousin.
Third cousins are fairly common, and many people may have third cousins without even realizing it. While they are more distantly related than first or second cousins, they can still share common ancestors and family history.
Understanding the specifics of different family relationships can be helpful for tracing one's family history and understanding genetic inheritance. Third cousins, for example, share a set of great-great-grandparents, which can provide clues to one's ancestry and family tree.
It's worth noting that third cousins may be more or less genetically related depending on the specific ancestry and family tree. For example, if two people share multiple common ancestors, they may be more closely related than typical third cousins. Conversely, if they come from more diverse backgrounds or have more distant shared ancestors, they may be less closely related than typical third cousins.
In conclusion, a third cousin is the child of one's parent's second cousin, or the second cousin of one's own grandparent. They share a set of great-great-grandparents with you and can provide clues to one's ancestry and family tree.
