YOU SAID:
I killed your son because he is a very dumb person
INTO JAPANESE
あなたの息子を殺したのは、彼がとても頭が悪いからです。
BACK INTO ENGLISH
I killed your son because he is so stupid.
INTO JAPANESE
あなたの息子を殺したのは、彼がとても愚かだからです。
BACK INTO ENGLISH
I killed your son because he is so stupid.
You've done this before, haven't you.