Interesting conversion

I heard a short conversion between Keke and her dad when I was cooking last night. I don't know how this conversion started...

Keke: When did your grandma died?
Dad: a long time ago, 15years ago...
Keke: When did your mom died?
Dad: She is still alive, she is your grandma.
Keke: when will your mom die?
Dad: I can't answer you, only God knows.
Keke: what about you?
Dad: I don't know. Everyone will die someday.

Silent for a second, she came over telling me "everyone will die someday", just like telling me she learned a new word - serious and proud of herself she learned some new.

Did she learn the definition of "death" from movies she watched, or does this really mean anything to her? I don't remember the first time I had conversion about death... probably not at three and half.