YOU SAID:
Darth Vader is Luke's dad.
INTO JAPANESE
ダースベイダーはルークの父です。
BACK INTO ENGLISH
Darth Vader is the father of Luke.
INTO JAPANESE
ダースベイダーはルークの父です。
BACK INTO ENGLISH
Darth Vader is the father of Luke.
That didn't even make that much sense in English.