Early Childhood Performance and Parental Contributions

I've been listening (yes, listening) to the book "Freakonomics" by Steven D. Levitt and Stephen J. Dubner this past week in my car on the way to work. A fascinating look at social phenomena from an economist's point of view. Among many other things explored in the book, the authors examine the impact that parents have on the intellectual development of childen, particularly during the "most formative" years between birth and kindergarten. They use a massive data set - the Early Childhood Longitudinal Study (ECLS)- collected over the past decade in a very large cohort of children in the US to determine what parental factors contribute to a child's success in school (at least in elementary school). The results are surprising in some ways because they refute some of the "conventional wisdom" regarding parental behaviors that are believed to increase a child's chances of success in school.

Eight factors that appear to matter (and were significantly correlated with performance):
1) The child's parents' educational attainment (positive correlation)
2) The child's parents' socioeconomic standing (positive correlation)
3) The child's mother was > 30 years old when she had her first child
4) Low birthweight (negative correlation)
5) The child's parents speak English in the home
6) The child is adopted (negative correlation)
7) The child's parents participate in the PTA
8) The child's parents have many books in the home

Eight factors that do not appear to matter (e.g. no correlation was found):
1) The child's family is intact (e.g. mom and dad are married and live in the same household)
2) The child's family recently moved to a better neighborhood
3) The child's mother did not work from the child's birth to kindergarten
4) The child participated in HeadStart
5) The child's parents regularly take the child to museums
6) The child's parents regularly spank the child
7) The child regularly watches TV
8) The child's parents read to the child nearly every day

The authors contend that these data indicate that who the parents "are" is more important than what the parents "do" in determining how well their child will do in school. This would suggest that our intellectual ability and our performance in school is determined more by genetic and general social factors (e.g. socioeconomic class) than any specific behaviors that our parents engage in to prepare us for school. At least in childhood. But do these same factors hold true in adolesence, early adulthood, and beyond? Are we "formed" early in our lives and the path of our existence irreverisibly established? Or do other factors play more important roles later in life? And most importantly, from my perspective as a teacher, does the power to develop and grow primarily reside within the learner or is it determined by the environment created by the teacher. What do you think?