Test your IQ

Yesterday, I went to Tapah, Perak with my family, for a family reunion in my mom's uncle house. One of my aunts, Makcik Ina sent an SMS to maklong. It sounded something like this:

_______________________________________________
Test your IQ.

David is the son of Jane.
Jane is the ___ of David's mother.

Fill in the blank with an appropriate word.
_______________________________________________

And, everyone was guessing the answer. And at last, I got the correct answer. ^_^

Hint: Think outside the box.
Answer: name <--Highlight the word to see the answer.