Revisiting Judith Harris

through Razib Khan posts since he often posts on topics taking latest work into account How Your (Sub)Cultures' Values Are More Important Than Family Values There is also a more recent shorter one Just because it’s not hereditary does not mean you can affect it
From the first post:
"To make it concrete, imagine across the population variation of personality is 30% heritable, 15% accounted for by shared environment, and 55% explained by non-shared environment. The parental effect is captured in the shared environment. When behavior geneticists downplay the role of parents in affecting outcomes, they are doing so because of this value. In this example the proportion explained by the parents’ genetic variation is twice as large as the conscious environmental choices. But, note that most of the variation is not necessarily due to genetic factors!

What is this variation? The short answer is that we don’t know. One hypothesis, promoted by Judith Rich Harris in The Nurture Assumption, is that it is one’s social milieu. That is, peer groups. To my knowledge in the past 15 years there has not been much support for this thesis, suggesting to me that we’re still at a loss to explain non-shared environment. In fact it may just be an intractable stochastic aspect of life outcomes (or if you want to reduce it to biology, developmental stochasticity)."

Check also 10 questions for Judith Rich Harris from 2006. Her book The Nurture assumption available online here and Website about the topic.