Arriving to my sister’s apartment, I always knock on the door and then open it without waiting for an answer, and it is always unlocked.

My sister and her husband, having known I was on my way over, shout hello from wherever they are in the house.

But my one-year-old nephew, not knowing when any visitors might arrive, gets a little jolt of joy and shock when he sees me. When he looks up from playing on the living room floor to see who’s at the door, it’s like a little current of electricity runs through him and his face lights up in surprise: no one told me YOU were coming over!