[SengirV]

The point is that people wouldn't suddenly diappear in front of you if their grandparents were killed before their parents were born. They would simple not even exist in your memory to begin with, since they never would have existed. Any reliance on SciFi writting is laughable to the point of being ignored.

[RegulatorCountry]

"Any reliance on SciFi writting is laughable to the point of being ignored."

You're being a bit over-serious, to the point of dour, here. The author's reference was tongue-in-cheek, specifically due to the science fiction popularized in books and film.

[Erasmus]

The point is that people wouldn't suddenly diappear in front of you if their grandparents were killed before their parents were born. They would simple not even exist in your memory to begin with, since they never would have existed.

This is apparently related to the laws of genetics, to wit: If your grandparents never had children, neither will you.