Disclaimer: "The Lord of the Rings" sadly isn't mine. But I hope Tolkien is okay with borrowing some of his characters.
Information: The story takes place before "The Lord of The Rings".
xxxxxxxx
Difference of opinion with an elf
"You are not allowed to marry her!" Elrond cried franticly after he heard of the marriage plans of his youngest son. "she's your sister! That's incest!"
"Ada, you know exactly that we are not related by blood!" The other one said exasperated. "Or did you forget that you have adopted me when I was small?"
"She's still your sister!"
"But because we are not akin, I am allowed to marry her!"
"But you are akin!" Elrond interjected. "you are my brother's child! This would still be incest!"
"Ada" Argued the other. "I might be your brother's descendant but there are a lot of generations between him and…"
"That doesn't change a thing! I don't care how many generations are between you and my brother – you are still my brother's child! As a near relative you are still not allowed to marry your sister!"
"Ada…"
"No! That's the end of this discussion!"
Aragorn sighted and cursed again that his family was of elven kin. When confronted with elfish opinions of kinship everyone would go mad!