"Leaving your young kids unsupervised most of the time.
I remember at 5 years old sitting in the parking lot of the bowling alley in my dads car for 3 hours while he was inside bowling. Also, most of the time, my parents had zero clue as to where I was. I would leave the house in the morning on my bicycle and be home for dinner. Suited them just fine."
or sand and gravel.