YOU SAID:
The boy’s stepfather is a grasshopper.
INTO JAPANESE
その少年の義父は草なぎだ。
BACK INTO ENGLISH
The boy's father-in-law is a grasshopper.
INTO JAPANESE
その少年の岳父は草なぎである。
BACK INTO ENGLISH
The boy's father-in-law is a grasshopper.
That didn't even make that much sense in English.