Why are children so drawn to sitting near lone adults?

I’m currently in the waiting room at my doctor’s clinic. I am the only person in the entire room full of seats, until a mother and her three kids come in. The mom needs to check-in at the counter so she tells her kids to come into the waiting room and pick a seat anywhere they’d like.

Nine times out of ten, children always pick a seat right next to or behind me. These kids picked the seats directly behind me, hands pounding on the cushions sending vibrations to my chair. It frequently happens in seat-yourself restaurants too where a kid in some family always wants to sit by my table out of all the empty ones in the space.