YOU SAID:

Your sister is the one who is stupid.

INTO JAPANESE

あなたの妹は愚かな人です。

BACK INTO ENGLISH

Your sister is a foolish man.

INTO JAPANESE

あなたの妹は馬鹿です。

BACK INTO ENGLISH

Your sister is an idiot.

INTO JAPANESE

あなたの妹はばかです。

BACK INTO ENGLISH

Your sister is an idiot.