What is a 3rd Cousin Once Removed?
Back to Genealogy Primer

We have all heard terms like this before but do we really know what they mean? It is even hard to figure out what a second or third cousin is never mind adding once or twice removed. Hopefully I can help explain all that.

First of all, we do most often understand that a cousin is actually a "first cousin" and this is because we would share the same grandparents. Now our second cousins share the same great grandparents that is to say they would be grandchildren of our grandparent’s brother or sister (or our great-aunt or great-uncle). Third cousins work the same way in that we would share great-great grandparents. My "cousin", Cheryl and I are sixth cousins – and we share the same great-great-great-great-great grandparents William McNairn and Agnes Chesney. It gets confusing with all those "greats" in there but to figure out what cousins you are – just count the total number of g’s – In this case there are five g’s for the greats plus one for the grandparents so that is six g’s all together.

To make life even more confusing, sometimes you will see the term once removed or twice removed etc. When we figure out cousins like we did above the one thing is that the two people are in the same generation. The term "removed" is used to describe when the relationship for the two people is that they are not from the same generation, for instance my father’s cousin is my first cousin once removed. This is because my father and I are one generation apart. My Grandfather’s cousin is my first cousin twice removed because my grandfather and I are two generations apart. Likewise, my great-grandfather’s cousin would be my first cousin three times removed. Cheryl (who I mentioned before) and I each have children. Cheryl’s children are my 6th cousins once removed – because there is a difference of one generation. This is the same as my children’s relationship with Cheryl. The interesting thing is that once you look at the fact our children are all in the same generation – they are 7th cousins of each other.