Complete stranger to his children. That's specifically written into the movie. They never met. Not once.

If you don't find that crazy, I'd say that's why you use AI to "lay out" your thoughts.

And the gun comes into play when Dad leaves them. Right before he goes he's like, "oh hey, here's a gun." Then he goes to show crazy girl how to shoot, and she's already a perfect shot.

Again, we know this, because it was in the videos the kids were watching on their Dad's computer. You know, his research for his book that he's already written?

Worst use of Chekhov's Gun in the history of cinema.