YOU SAID:
when's the last time your dad was black
INTO JAPANESE
あなたのお父さんが最後に黒人だったのはいつですか
BACK INTO ENGLISH
When was your dad last black
INTO JAPANESE
あなたのお父さんが最後に黒人になったのはいつですか
BACK INTO ENGLISH
When was your dad last black
That didn't even make that much sense in English.