Your grandmother, while still a fetus smaller than a grown man's foot, had in her just developed ovaries all the eggs she would ever in her lifetime have.
One of those eggs in Grandma's new ovaries, there in your great-grandmother's womb, was the egg that, with the help of your grandfather, became your mother. (The same is of course true for your father, his mother, and his grandmother.)
You're physically a lot closer to your grandmother (and your great-grandmother, for that matter) than you think.
That is all.
• Image of old woman wishing I'd shut the hell up about her ovaries from here.