How much of this gap is explained by the fact that low-income earners have to work harder and thus have both less time to interact with their children, and less

How much of this gap is explained by the fact that low-income earners have to work harder and thus have both less time to interact with their children, and less money to hire other humans to interact with them? Consider a wealthy "Leave it to Beaver" one-income family: dad works, mom stays at home and drags the tots to an endless series of carefully selected enrichment activites, maybe drops them off at a Montessori day care a few days a week. While at the other end of the social scale, single mom works two jobs to make ends meet and is barely ever home, so kids are left with a relative who's taking care of a whole brood of children, or plunked down in front of the TV and told to keep quiet.