People of the same generation who share the same grandparents are cousins...if they have the same great grand parents but not the same grand parents, they are 2nd cousins....if they share the same great great grandparents, they are 3rd cousins etc.
The once removed part comes when the "cousin is from a different generation. For example my mother's first cousin is my 1st cousin once removed.

It's still confusing. I have to draw a family tree to figure out who is what, LOL.

It can work like this too.....
My son found out that he and his fiance were third cousins, they got married anyway. So his children are not only son and daughter, but his third cousins, once removed.

His wife is not only my daughter-in-law, but my second cousin, once removed. And the Kids are my second cousins, twice removed.

This sort of thing is important to a lot of people. I don't understand it or care. The kids did inherit all the good genes from the shared links. Only time will tell if the bad genes are lurking around somewhere.

Linda, thanks for your explanation; like Anneliese, I still find it confusing, tho. I have known how to figure relationships by using the "once-removed" thing, but not applied it in terms of grandparents.

Agnes, your explanation about your son's family's boggles my mind!!

just to make it a little more confusing.... and please remember that these people lived w-a-a-a-y back in the mid 1800s.....

The DIL's father and I turned out to be second cousins..BUT while we both had the same great great grandfather, there were two wives. That would make it simple, right??? well, the DIL's father was descended from the first wife and his mother was sister to the man that my grandmother (from the second wife) married. I don't even want to try to sort that one out.

They were from the Low Country area of SC and the original families settled there in the mid 1700s. You married anyone that was available and most everyone was some kin to everyone else.

How many of you remember the old song..."I'm My Own Grandpa."? I guess it happened often in the Good Old Days.

Yes, I remember the song. But now a more confusing question. My oldest daughter asked me What is my relationship to your second cousin?".. Told her she was adopted, the thought makes my head hurt.

Gandle, there would be no blood relationship of course, and I am guessing at the "family" relationship.... She would be be your second cousin's once removed second cousin.

It works sort of like this...if no one does anything unusual.

A and B are brother and sister.
Their children are first cousins.
The first cousins children are second cousins
Second cousins children are third cousins...and so on..

Now, this is where it gets mixed up and I am not sure I am right. It's how my mother figured it.
The second cousins are the first cousin's first cousins once removed.
The third cousins are the first cousin's first cousins, twice removed.

I think the oldest generation sets the cousin-ship, and then the first removed, second removed, etc, determines the step downward through the generations. I don't think it moves upward...just downward.

This whole thing makes my brain hurt. My cousin in Norway is the family historian and he has used one of the heritage type sites to draw the family tree, and it goes back to 1800.
He does the Norwegian side , and his daughter, (I'm guessing she's my second cousin) does the American version.
Both of them have been here to visit us in person and that's special.

Your second cousin is your daughter's second cousin, once removed.
Linda C

Happened to read this the other day, then it came up in conversation last night. I was ready. Thanks for the discussion!

Ouch, think I will let my cousin work it all out and let us know.

And then, you sometimes ran into the double first (or second or whatever)cousin. That happened when siblings of one family married the siblings in another.