Obama's relationship with his southern grandfather was nice if you read his autobiography the way he was welcome was wonderful
He is your Grandfather, and is your son's Great-Grandfather.
You can't have a grandfather 5 times removed. You could have a 5Great grandfather. In which case the relationship would be your 3Great Grandfather.
your great great great great grandfather
Your Grandfather or your Great Uncle.
Your grandfather's brother is your great uncle
Your grandfather's great nephew is your second cousin.
It could be your grandfather. Or it would be a great uncle.
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Your great grandfather's brother is your great great uncle.
Grand Aunt .
Your great grandfather's great niece is your 3rd cousin.
Third cousins once removed.