"The Battle of Waterloo was won on the playing-fields of Eton."
Separated-identical-twin studies have pretty much given us the amount of personality that's heritable (about half). The rest is…. what?
Harris thinks the answer lies in the social group the child grows up in. The Waterloo/Eton quote is an anecdotal example of this. She uses the children of the British upper class as a prime example of children who are, essentially, not raised by their parents but by nannies, then a peer group and an entire system of schools that have been around for centuries, turning out adults similar to their parents, even though they barely saw their parents during their formative years.
Another example Harris loves is the children of immigrants. Their parents never lose their accents, may never learn to speak the new language fluently at all, and hold to the ways of the old country, but the kids -- as long as they arrive before puberty and are not completely surrounded by nonnative speaking kids -- become indistinguishable from nonimmigrant adults in their language and cultural attitudes.
How many children does it take to constitute a group? It depends on how big the larger whole is. According to Harris, in traditional societies, children were basically on their own with the child group from the ages of 3 through puberty. Older siblings would watch out for the youngest ones until they got up to speed. If there were enough kids, they would break into groups by age and sex, sometimes with the younger kids in a single group and the older kids sex-segregated. But if there weren't enough kids, then they would just be one group, differentiated only from the adults.
Groups of kids form for little or no reason. Famous examples from psych research include the Robbers Cave study and the overestimators and underestimators experiment. Once groups form, they become more different from each other through "group contrast effects":
All it takes to produce group contrast effects is to divide people into two groups. The groups will inevitably see themselves as different from each other, with the result that any small differences between them will get larger. The interesting case is when the groups start out exactly alike, because if there are no real differences to begin with, the groups themselves create them (page 123).The role of schools in all of this is of particular interest. Mostly, schools are just a place for the peer group and general societal mores to do their work. Harris's hypothesis is that humans find a group to identify with (even if the group won't have you as part of it), and that group socializes each individual. In schools, it's very easy for those groups to form around perceived intellectual haves and have-nots, since learning is what everyone is there for. In a racially stratified society, it's also easy for those groups to form along race lines, correlating to school-positive and school-negative attitudes. This may sound familiar.
But Harris does say that sometimes teachers can be leaders of their students, breaking up those groupings and tendencies. The famous examples of Jaime Escalante or Rafe Esquith may well be times where the teacher became the leader of the group.
(I had such an example from my own life, although he wasn't, in my opinion, trying to lead us in a good direction. My fifth grade teacher was a jock who drilled us in sports during classroom hours. He broke us of the habit of playing in gender-based small groups during recess, over time getting every kid in the class except me and one other smart but physically challenged girl to play organized touch football instead of playing tag or doing the monkey bars. He left teaching a year later to become part of the all-white team that always lost to the Harlem Globetrotters. No kidding.)
source). In addition to 200 instruction days that last from 8 a.m. to 4:45 p.m., Harvest uses uniforms to prevent group segmentation. Students are addressed as "scholars," and weekly awards recognize achievement and helping other students. Grades 7 and 8 are a boys-only program called Best Academy, which works hard on creating a culture where academics are the highest value. The school's overall math and reading test scores, while nowhere near 100 percent, are much higher than schools with comparable demographics. Of course, there is parent self-selection at work in the composition of the student body, but their results are still notable.
I find Harvest Prep's drill-and-kill methods and emphasis on testing problematic, but the effort to build a culture where the primary value is academic achievement seems like the right approach to me. Private schools automatically have this because they use selective admissions to make sure their students have the right attitude to start with.
It seems to me that the short-term solution to fixing the school achievement gap -- in addition to quality early-childhood education so kids who start out with less have a chance to be close to even by kindergarten -- is preventing group divisions that form around pro-school and anti-school attitudes. Harris advocates "giving kids harmless ways to split up -- Dolphins versus Porpoises -- rather than harmful ways" and to "keep the social categories in balance so that they cancel each other out. If a child can't decide whether she is a girl, a Dolphin, or a dummy, she may end up categorizing herself simply as a member of Ms. Rodriguez's sixth grade class" (page 247).
Judith Rich Harris has a lot to say about a lot of things. I hope to follow up with a few more posts on The Nurture Assumption and her later book, No Two Alike, which attempts to answer the question of why identical twins are often not identical.