What does "therefore" mean in this context?

Question

I was watching a Ted lecture titled "Jarrett J. Krosoczka: Why lunch ladies are heroes" and came across this paragraph.

And she looked at me, and I could tell that she recognized me, but she couldn't quite place me, and she looked at me and she said, "Stephen Krosoczka?" And I was amazed that she knew I was a Krosoczka, but Stephen is my uncle who is 20 years older than I am, and she had been his lunch lady when he was a kid. And she started telling me about her grandkids, and that blew my mind. My lunch lady had grandkids, and therefore kids, and therefore left school at the end of the day?

I don't understand what he meant by "and therefore kids" both grammar-wise and meaning-wise because as far as I know, "therefore" should have a full sentence.

Can anybody explain this to me?

Thank you!

Answer 1

If she had grandchildren, it was self-evident that she must have had her own children (to be the parents of those grandchildren). The "therefore" reflects that implicit syllogism. And if she had had her own children, that meant she could not have been a mere fixture of the school but a human being with a life of her own ("she left school at the end of the day"), hard as that was to believe! ("That blew my mind.")

The commonplace idea presented here is that children often do not realize that the people they encounter at school have lives outside the school. They think of the lunch lady as no more than the person behind the counter who serves them food. The realization that these fixtures are real people with their own concerns comes as something of a shock to the young mind.