I recently spoke with a newly diagnosed woman who was having trouble understanding her teenage girls’ reaction to the news that their mom has cancer. She reported that when she told the girls the date of her surgery, the older one received the news silently, while the younger responded, “Mom, that’s my first basketball game. Does that mean you won’t be there?!”

I assured this woman that her girls sound very typical, based on the anecdotal evidence of my own experience, as well as...