I learned recently about the provocative books of Judith Rich Harris, “The Nurture Assumption” and “No Two Alike,” which are discussed in Matt Ridley’s quirky “The Evolution of Everything.” Harris analyzed a substantial accumulation of research and draws new conclusions about the old nature/nurture debate.

It turned out that about 50% of a person’s personality can be attributed to the genetic inheritance passed down to the individual by Mom and Dad. But the other 50% comes from living life. Often, this has meant that Mom and Dad have also gotten praise or blame for the directions in which the twig is bent.

Harris begs to differ. indeed, her analysis of voluminous research, twin studies and the like, suggests that the usual explanations don’t account for the personality traits adults display — not birth order, home environment (except in horrific cases of abuse or deprivation), nor even chance.

Rather, one variable previously slighted seems to carry the most weight, after genetic inheritance, and it is socialization, particularly as learned through interaction with peers. From the other children that children hang with, they learn social habits, speech patterns, and cultural touchstones.

So, Mom and Dad were right to worry about the bad influence of that kid down the block. But the research suggests an even more interesting truth. One of the most important things in going forward in life appears to be learned in the teenage years.

Harris suggests this is when young people begin to understand their relative status within their peer group. And the conclusions they draw about their status, their place and possibilities in life, affects their future behavior and can become a self-fulfilling prophecy.

I suspect most of us, upon considering this notion, will realize it has a creepy ring of truth. For those who were happy, successful, and popular in Middle and High Schools, this will seem only just. Yes, that was when their wonderfulness was recognized, and how right their peers were to value them.

For many more of us, regarding the rather repulsive, alienating teenage years as an incubator for our lifelong feelings of self-worth will induce horror and despair. It is bad enough that these were definitely not the best years of our lives, but to suppose they also foretold our future prospects adds insult to injury. It’s like a psychological form of Calvinist predestination.

Luckily, it may not be quite that bad. Luckily, those years, as we all recall, were full of various cliques, clans, and tribes, so that a kind of self-sorting was possible. Except in the direst cases, rather than discovering that you fit nowhere, you probably discovered to which caste of kindred spirits’ ‘somewhere’ you belonged.

Still, it remains a rather alarming notion that our feelings of status, belonging, worth, and prospects in life are largely derived as teens from other teens. These creatures are, after all, half-formed, ill-informed, emotionally volatile, intellectually immature, needy, confused, arrogant, anxious. And yet, according to this theory of development, it is a jury of these peers that we consult in deciding who we are, where we stand, and how we fit in.

The theory certainly accounts for how hard it is to alter the trajectory of teens in dysfunction ghettoes of poverty or deprivation. For that matter, it also suggests that teens attending posh private schools in wealthy enclaves, church academies in the South or rural public school on the great plains may each be unconsciously taught their place by peers with quite different values and attitudes. Of course, there are always a few, as author Merle Miller once noted, who never fit in where they find themselves and happily flee at the first opportunity to places more to their taste.

Many of us, a few years after high school, are appalled to realize that we ever cared what those dopes we hung around with thought about us, or anything else, but that doesn’t mean we weren’t influenced by it, if Harris is right.

Kurt Vonnegut Jr., in a funny essay from the 1970s, noted that he, or perhaps his wife, went to the same high school as Melvin Laird, who was by then the Secretary of Defense in charge of bombing Southeast Asians for the Nixon administration.

Scales fell from Vonnegut’s eyes, in his telling, when this caused him to realize that the people running the world were the same idiots he used to sit next to in class, get bullied by in gym or avoid at the sock hop. And chills ran down his spine.

If there’s truth to the notion that we are all shaped by the subtle, even unspoken feedback of our teenage peers, and it appears there is evidence to support the idea, there probably isn’t much we can do about it decades later. But we can plot and connive to expose our kids only to peers with taste and discernment. Or since that seems unlikely to be found in teenagers, we can figure out how to keep them away from other teenagers altogether until they are twenty-five or thirty.