Crime stories are our version of sitting round a camp fire and telling tales. We enjoy being scared under safe circumstances. That's why there's no tradition of crime writing in countries that have wars.
A life-long blessing for children is to fill them with warm memories of times together. Happy memories become treasures in the heart to pull out on the tough days of adulthood.
I'm not a marketing person. I don't ask myself questions. I go by instinct.