If you are at all like me, your first reaction to this unqualified statement may be concern with its unlimited breadth and depth, and its implications.The punch line is that, at least within the normal range of parenting styles, how you raise your children has little effect on how your children turn out. You can be strict or permissive, involved or distant, encouraging or critical, religious or secular. In the long run, your kids will resemble you in many ways; but they would have resembled you about as much if they had never met you.
--Professor Bryan Caplan, "Good News and Bad News on Parenting," The Chronicle Review
And it's not as if I have failed to keep up with the research and reporting. It's not as if I have been unaccepting or hostile toward the determinism inherent in the genetic prescriptions and probabilistic predispositions that have evolved and been conveyed from generation to generation. I am in fact much persuaded by the deterministic realities of evolution and genetics. But I further accept the deterministic qualities, the shaping processes, of our environments as well: acculturation, education, classical and operant conditioning. These too can and do change our behavioral profile, sometimes markedly. At least that is what other credible research has long indicated. And it has always made empirical sense to me, as well. So, does the evidence adduced in this article challenge those understandings about the role of environment, including parents?
First, it is important to be clear what these research findings say and what they do not say. If I understand them, the findings do not say that the importance of parental roles is negligible, but rather that the differences in approaches to parenting, "within a normal range of parenting styles," is of negligible consequence. Of course, that is still a surprising conclusion, at least for most people.
According to George Mason U. economics professor Bryan Caplan, there are now research methodologies employing "high-quality time-diary studies going back about 40 years, which make it possible to fact-check popular perceptions about the evolution of parenting." These studies have shown that despite concerns expressed about this generation of parents and children, parents in 2000--mothers, fathers, and working moms--spend much more time with their children than parents in 1965 and 1975. And sociologists have roundly applauded this as a good thing for families and children. But Caplan sets up that straw man just to introduce evidence that the sociologists are wrong--not that spending more time or better time with children harms them, but that it just doesn't matter.
The good professor then brings to our attention recent studies that have addressed the impact of parenting on children. He reviews how they had to address separating the commingled effects of nature and nurture--genes and environment (including parents)--on the children. They did this by employing the long-recognized approach of seeking out subject families with one or both identical twins (the same genes), fraternal twins (half the same genes), and adopted children (no genetic relationship). They then did a lot of comparisons. Employing and improving these twin children and adopted children methodologies, the researchers believe they have found credible, reliable answers to questions about the relative importance of genetic endowment and parenting approaches in shaping the behavior and characteristics of children as they grow to adulthood. And in the author's view, the findings support the conclusion that, "nature wins."
Heredity alone can account for almost all shared traits among siblings. "Environment" broadly defined has to matter, because even genetically identical twins are never literally identical. But the specific effects of family environment ("nurture") are small to nonexistent. As Steven Pinker, a professor of psychology at Harvard University, summarizes the evidence:"First, adult siblings are equally similar whether they grew up together or apart. Second, adoptive siblings are no more similar than two people plucked off the street at random. And third, identical twins are no more similar than one would expect from the effects of their shared genes."
...Recent scholarship does highlight some exceptions. For example, while earlier researchers found that divorce runs in families for purely genetic reasons, some new studies find that both nature and nurture play a role. Another study finds that controlling for genes, run-of-the-mill spanking does no lasting harm, but harsh physical punishment can leave lasting psychological scars. But even if many exceptions accumulate, the fact remains that people tend to greatly overestimate the power of nurture.
Of course, I can only surmise from this summary article that what are measured and compared are basic behavioral characteristics. It's not disclosed just which characteristics are deemed defining or how they are defined. But these reported results in this article suggest that genes prescribe all such behavior and characteristics, as opposed to the view that some genes only predispose individuals toward some of that behavior or some of those characteristics--or that some behavior is not explained by genes at all. My clear understanding, however, is that while genetic studies have identified prescribing genes, they have also identified others which only predispose individuals toward certain behavioral characteristics. Often those predispositions are a function of the combined effects of several genes. In those cases, the actual result and probability is determined in part, at least, by a particular environment's triggering, acculturating or conditioning features. Often enough, only environmental factors can account for some behavior or characteristics. And it is the estimable Professor Pinker, cited herein by the author, who has so often made this very point in his books and articles.
What I'm questioning, I suppose, is whether the author--working outside his discipline--has examined carefully the studies he cites, and from which he concludes. Did he consult the original research and the qualifications which are always noted there? Did he review other relevant studies in the area and on the topic? Did he compare these more comparative, deductive studies with the extensive work and results of those studying the human genome and the effects of specific genes studied from a more inductive perspective? You'd think he must have, right? But who knows? Regardless, this article appears more an ad hoc merging of summary, headline results, and just does not have the ring of scientific credibility to it or, at least, a sense of the whole story or complete picture.
It seems likely that the good economics professor formed his summary views, in part at least, from the work of the aforementioned Steven Pinker of Harvard--work like "My Genome, Myself," recently published in the New York Times Magazine (1.11.09). That piece is about "consumer genetics" and the Personal Genome Project, and spends considerable time discussing what a personal genome profile can and cannot tell you. And as I've suggested, Professor Pinker's conclusions are not nearly as simple or clear as Professor Caplan would have us believe:
Nor should the scare word “determinism” get in the way of understanding our genetic roots. For some conditions, like Huntington’s disease, genetic determinism is simply correct: everyone with the defective gene who lives long enough will develop the condition. But for most other traits, any influence of the genes will be probabilistic. Having a version of a gene may change the odds, making you more or less likely to have a trait, all things being equal, but as we shall see, the actual outcome depends on a tangle of other circumstances as well....
With personal genomics in its infancy, we can’t know whether it will deliver usable information about our psychological traits. But evidence from old-fashioned behavioral genetics — studies of twins, adoptees and other kinds of relatives — suggests that those genes are in there somewhere. Though once vilified as fraud-infested crypto-eugenics, behavioral genetics has accumulated sophisticated methodologies and replicable findings, which can tell us how much we can ever expect to learn about ourselves from personal genomics.
...a substantial fraction of the variation among individuals within a culture can be linked to variation in their genes. Whether you measure intelligence or personality, religiosity or political orientation,
television watching or cigarette smoking, the outcome is the same. Identical twins (who share all their genes) are more similar than fraternal twins (who share half their genes that vary among people). Biological siblings (who share half those genes too) are more similar than adopted siblings (who share no more genes than do strangers). And identical twins separated at birth and raised in different adoptive homes (who share their genes but not their environments) are uncannily similar.Behavioral geneticists like Turkheimer are quick to add that many of the differences among people cannot be attributed to their genes. First among these are the effects of culture, which cannot be measured by these studies because all the participants come from the same culture, typically middle-class European or American. The importance of culture is obvious from the study of history and anthropology. The reason that most of us don’t challenge each other to duels or worship our ancestors or chug down a nice warm glass of cow urine has nothing to do with genes and everything to do with the milieu in which we grew up. But this still leaves the question of why people in the same culture differ from one another.
At this point behavioral geneticists will point to data showing that even within a single culture, individuals are shaped by their environments. This is another way of saying that a large fraction of the differences among individuals in any trait you care to measure do not correlate with differences among their genes. But a look at these nongenetic causes of our psychological differences shows that it’s far from clear what this “environment” is.
Behavioral genetics has repeatedly found that the “shared environment” — everything that siblings growing up in the same home have in common, including their parents, their neighborhood, their home, their peer group and their school — has less of an influence on the way they turn out than their genes. In many studies, the shared environment has no measurable influence on the adult at all. Siblings reared together end up no more similar than siblings reared apart, and adoptive siblings reared in the same family end up not similar at all. A large chunk of the variation among people in intelligence and personality is not predictable from any obvious feature of the world of their childhood.
Think of a pair of identical twins you know. They are probably highly similar, but they are certainly not indistinguishable. They clearly have their own personalities, and in some cases one twin can be gay and the other straight, or one schizophrenic and the other not. But where could these differences have come from? Not from their genes, which are identical. And not from their parents or siblings or neighborhood or school either, which were also, in most cases, identical. Behavioral geneticists attribute this mysterious variation to the “nonshared” or “unique” environment, but that is just a fudge factor introduced to make the numbers add up to 100 percent.
No one knows what the nongenetic causes of individuality are. Perhaps people are shaped by modifications of genes that take place after conception, or by haphazard fluctuations in the chemical soup in the womb or the wiring up of the brain or the expression of the genes themselves. Even in the simplest organisms, genes are not turned on and off like clockwork but are subject to a lot of random noise, which is why genetically identical fruit flies bred in controlled laboratory conditions can end up with unpredictable differences in their anatomy. This genetic roulette must be even more significant in an organism as complex as a human, and it tells us that the two traditional shapers of a person, nature and nurture, must be augmented by a third one, brute chance.
The discoveries of behavioral genetics call for another adjustment to our traditional conception of a nature-nurture cocktail. A common finding is that the effects of being brought up in a given family are sometimes detectable in childhood, but that they tend to peter out by the time the child has grown up. That is, the reach of the genes appears to get stronger as we age, not weaker. Perhaps our genes affect our environments, which in turn affect ourselves. Young children are at the mercy of parents and have to adapt to a world that is not of their choosing. As they get older, however, they can gravitate to the microenvironments that best suit their natures.
To be fair to Professor Caplan, then, I would grant that general conclusions suggesting parenting is often overdone have the ring of validity to them. And don't we often observe and reflect on the resilience of children and how they seem to work past, shake off, or overcome their upbringing to become the people they had to be? For, doubtless, genes do play a significant if not dominant role in shaping the behavioral characteristics of the people children grow up to become. But, to some extent, so does culture, family environment, and other seemingly random factors. There is substantial, credible research evidence to support these conclusions, as the authoritative Professor Pinker attests.
And I am willing to take Professor Caplan's more temperate, more general concluding statement as reasonable, as far as it goes, and as capturing a piece of societal reality as it likely does--even if it doesn't acknowledge the contributing role played by "environment."
Many of us worry that our nation will pay a heavy price in years to come because modern parents are shirking their responsibilities to the next generation. If you combine the results from time diaries and behavioral genetics, however, you get a different picture. It turns out that there is some really good news and some mildly bad news. The really good news is that we can stop worrying about the horrible fate of the next generation. The bad news is that parents today are making large "investments" in their children that are unlikely to pay off.
http://www.nytimes.com/2009/01/11/magazine/11Genome-t.html?_r=1&pagewanted=all
