What is a third cousin?

A third cousin is someone who shares a great-great-grandparent with you. This means you and your third cousin have four generations separating you from your common ancestor. You'll share very little DNA with a third cousin, often not enough to be reliably detected by DNA%20testing.

Essentially, your grandparent's%20cousin's child is your third cousin. The degree%20of%20relationship is quite distant, and you are unlikely to know them unless you are actively researching your genealogy.