The New York Times has an article about the influence of genetics on behavior. It's a synthesis of a number of recent studies implicating a genetic relationship between predispositions for a number of different phenomena, from "wild streaks" to obesity.
ScienceBlogs' own Jonah Lehrer has already written an impressive response, noting that most of the genetic effects described in the article are small and unreliable.
Even more interesting, the Times article actually cites a blog post inspired by our own Razib. This is probably the most heavily linked New York Times article I've ever seen -- is the Times finally "getting" new media?
But it does beg the question -- is the MSM as susceptible to the "buzz" of the blogosphere as the blogs themselves? And what does this mean for reporting? Clearly reporters are reading the blogs and using them as inspiration for stories. Will objectivity suffer? Or is this just a new conduit for the same old media biases we've seen from time immemorial?
Coming back to the question of genetics and behavior, Greta and I like to look at it this way. Supposing genetics account for 90 percent of behavior and we can influence the remaining 10 percent through teaching and other forms of behavior modification. Wouldn't we still want to work just as hard to teach kids to behave, or to learn math, or avoid sweets? If we knew our efforts only had a small effect, shouldn't we just try that much harder?
I suspect the influence of genetic variation on behavior is somewhat smaller than that, but doesn't the same logic still apply, for any influence of genetics less than 100 percent?
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If the sociocultural influence is small enough, and the cost of exerting the influence is large enough, no matter how much we value the behavior, it will be prohibitively expensive to work to change behavior. And that's even assuming that we can reliably influence future behavior -- I am somewhat skeptical on that subject.
Genetic influence is almost certainly much, much smaller than 90%. Even if it is, timeframe matters. I would expect children to be relatively unaffected by genetic behavioral predispositions and adults more so, if only because experiential influences would be more likely to approach the mean as time increases. Children are also much less vulnerable to teaching than most people realize. As long as you don't stunt their intellectual capabilities, most of them are far sharper than adults.
If the genetic influence were significant and we could identify the predicted effects of the genetic influence, it might make sense to try to provide personal, tailored instruction that would help someone take advantage of their genetic makeup and help offset any disadvantages. Of course, it is troubling that someone might be discriminated against because they have genetic markers suggesting certain behaviors or behavioral issues especially when it is likely that the genetic impact is small.
I think the following equation has been discredited:
environment + heredity == 100%
Nevertheless, it is almost impossible not to think and write about the relative influence of environment and heredity without making the assumption that is implicit in the above equation.
Politically, I am as liberal as anyone and I am strongly in favor of parenting education, social program for disadvantaged people, etc. I believe that they do make a difference.
At the same time, I value evidence-based knowledge in regards to development and I see strong evidence for inherited individual differences. I worked for a long time to integrate my liberal sensibilities with my understanding of the academic literature. If I accepted that genes influence behavior, does that make me a nazi, or a racist like Karl Lorenz? One of the most important aspects of this was to discredit the assumption that environment and genes are independent factors that predict human development.
The following equation is a much more complicated and, I believe, appropriate way of viewing environment and genetic influences on human behavior:
environment*genetic + error = 100%
I was surprised that the article didn't cite Thomas Bouchard's (2004) analysis of the genetic basis for psychological behaviors. His article is must-reading for understanding the broad implications of genetics on behaviors -- even social attitudes. His analysis looks at studies of monozygotic twins separated at birth to control for the influence of environment and genetics.
To address some of the small-N studies, he used metaanalysis to combine them into larger studies. In his analysis, few things approach 90% genetic influence. I say "few" non none, because Schizophrenia comes in at 80%, and intelligence (only later in life) rises above 80%. Note the chart on page 3.
His article is downloadable here.
Bouchard, T. J. Jr. (2004). Genetic influence on human psychological traits: A survey. Current directions in psychological science, 13(4), 148.
Abstract--
There is now a large body of evidence that supports the conclusion that individual differences in most, if not all, reliably measured psychological traits, normal and abnormal, are substantively influenced by genetic factors. This fact has important implications for research and theory building in psychology, as evidence of genetic influence unleashes a cascade of questions regarding the sources of variance in such traits. A brief list of those questions is provided, and representative findings regarding genetic and environmental influences are presented for the domains of personality, intelligence, psychological interests, psychiatric illnesses, and social attitudes. These findings are consistent with those reported for the traits of other species and for many human physical traits, suggesting that they may represent a general biological phenomenon.
I fail to understand how genetics (not heredity) can be seperated from environment. Unless one is going to take some sort of dualist stance on brain and behavior, all behavior is ultimately the product of genetics. Sure, behavior can be altered by environment, but don't these changes ultimately boil down to regulation of genes be it through transcription or translational modifications? Alterations in behavior that are brought about by environmental cues require changes in the neural architecture (be it the creation of new synapses, pruning of others or alterations in signalling processes) -- a process that can not be seperated from genetics since it is dependent on regulation of genes and transduction mechanisms that are the consequences of the concerted action of gene products. Perhaps what I am saying is that heredity is a part of genetics but the words are not interchangeable and it creates confusion.
Not all behavior is ultimately the product of genetics. That's an absurd claim -- would you suggest that the language I speak has anything to do with my genes?
I have to agree with theodore price (above). To continue to pose the question in these terms is to reproduce a problematic split between the biology and the culture. If we have learned nothing from the combination of cognitive science with evo-devo, the genome project, and socio-biology, it is that our brains and bodies have evolved for culture, that each bind the other. Our cognitive (cultural) abilities are mediated through a body, and our cognition (culture) shapes the perceptions we have of our environments and bodies. Furthermore, our bodies/brains are set up to adapt to the environment (in fact, it seems that ours and other mammals' ability to pass on information (learning and culture) is our most powerful adaptation); and to adapt the environment to us. Given what we know about how genes work in cascade effects and like recipes and in a highly responsive way to the environment, it seems that the framing of the issue both in this post and the NYT is simply faulty.
The American Pragmatists' version of naturalism, especially John Deweys, worked tirelessly to rid scientific and social scientific epistemes of the mind-body/nature-nurture/biology-culture split. It doesn't exist and to continue to think in that binary will ultimately thwart our efforts to understand the real complexity of human behavior and cognition.