I really would like all the parents of Sophie's friends to read this interview:
The reason is simple - If our children are playing together, then they probably have much more influence on each other, than whatever you or I do.
Our influence on our kids is mostly already in their DNA - for instance, if you are left-handed, have perfect eyesight, enjoy reading Hegel, have violent tendencies or are allergic to peanuts, your biological children probably have inherited these traits from you. Studies of families who have adopted children from different biological parents seem to demonstrate that the adopted siblings, despite sharing the same home environment, are more no more likely to resemble each other than two complete strangers. And twins who were seperated at birth and raised by different families, still end up with very similar personality traits and IQ.
Of course, environment still has a role - an obvious example (I think Steven Pinker refers to it, but I cannot remember) is that if you plant cloned wheat plants in 2 different fields, and water and fertilize one field and leave the other neglected, then of course you get a completely harvests at the end of the season. However, this "environment" is only partly what your child does at home, and a good part of it is what happens when your kid plays with other children.
So, according to Ms Harris, once you discount any genetic predisposition to do so, if you want your kid to enjoy eating organic peaches and reading Hegel, then you have to make sure that your child's peer group enjoys these same activites. Otherwise, no matter how much organic tofu you pack in your kid's lunchbox, your kid will want to eat hamburgers and watch Disney if that is what this is what his/her friends do. This is probably still why people are going to try to send their kids to private schools or live in expensive neighbourhoods, as the biggest influence you can have on your children is to choose their friends !