Spend five minutes with a child asking a few questions and you can quickly learn what their family values, expectations, what’s allowed, and what’s frowned upon. Why is that?

Because a mirror works even when our eyes are closed.

Without having to say a word and without intending to, human nature has a way of expressing preferences, fears, political leanings, approval, annoyances, pleasure, and doubts without having to say a word. It’s in our reactions, a heavy sigh, how we spend, and what’s permis...