Ancestry/Genealogy

Reply #2 is correct. It all links back to the closest common ancestor.

Your Grandfather's Sister is your Great Aunt. I don't know which parent, but let's say your Mom for the sake of discussion:

- Your Great Aunt would be your Mom's Aunt
- Your Great Aunt's children would be your Mom's First Cousins

OK - hold that thought for a moment.

Let's say You have an Aunt (your Mom's Sister)

- Your Aunt's children would be your First Cousins
- Your First Cousin's Children are your Second Cousins
- Their Children are your Third Cousins...and so on

So when something applies to your parent's generation, it is "once removed"
- So your Mom's First Cousin (your Great Aunt's child) is your First Cousin, Once Removed
- If that Cousin has a child, it would be your Second Cousin, once removed.