The son of your grandson is your great grandson. You are his great grandmother or great grandfather.
Your father's great grandson could be your grandson, or your great nephew.
Your brother is a great great uncle to your great grandson. Your great grandson is your brother's great great nephew.
You Aunt is you grandson's Great-Great Aunt. Your grandson is your Aunt's Great-Great Nephew.
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
You and your great great aunt's great grandson are third cousins.
George Washington's great great grandson did not go to school. Washington had no children of his own so he had no great great grandson.
he is the grandson
You and your great uncle's grandson are second cousins.
Your sister is your grandson's great aunt. He is her great nephew.
Your great aunt's grandson is your second cousin.