On Saturdays, when the weather is not fit for the playground, I take my toddler to a tumble gym where he can run, climb, and kick balls around with other kids his age. Parents must accompany kids in the play area as this is a free-form play center without an employed staff (other than the front desk attendant). As a market researcher and a perpetual observer of the human condition, I’ve noticed that these parents fall into three distinct groups: the super-involved....