CHARLES MURRAY: Our Futile Efforts to Boost Children’s IQ. “How can parenting and socioeconomic status play such minor roles in determining IQ, when scholars on all sides of the nature-nurture debate agree that somewhere around half of the variation in IQ is environmental? The short answer is that the environment that affects IQ doesn’t consist of the advantages that most people have in mind — parents who talk a lot to their toddlers, many books in in the house for the older children, high-quality schools and the like. Instead, studies over the past two decades have consistently found that an amorphous thing called the ‘nonshared’ environment accounts for most (in many studies, nearly all) of the environmentally grounded variation. Scholars are still trying to figure out what features of the nonshared environment are important. Peers? Events in the womb? Accidents? We can be sure only of this: The nonshared environment does not lend itself to policy interventions intended to affect education, parenting, income or family structure.”