#54: Sleepwalkers?
I’ve known several sleepwalkers. You can ask them all day long if they did something the night before, and they’ll deny it with complete honesty. They have zero recollection because they aren’t conscious. I have a good feeling that’s what happened here. At age nine or ten, you wouldn’t think of that.

Any of the people in the family could be a sleepwalker. It could have been the brother, the mom, or the dad! Especially if the friend heard it, too. Either that or a draft came through the house and slammed the door, and then it bounced back open. Houses do weird things as they age!