5 replies to this topic

[stocks]

The most prominent finding of behavioral genetics has been summarized by the psychologist Eric Turkheimer: “The nature-nurture debate is over. . . . All human behavioral traits are heritable.” By this he meant that 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.

http://www.nytimes.c...mp;ref=magazine

[Rogerdodger]

Twin studies and my grandchildren have me agreeing.

[stocks]

The DNA of Politics
Genes shape our beliefs, our values, and even our votes


Children differ, as any parent of two or more knows. Some babies sleep through the night, others are always awake; some are calm, others are fussy; some walk at an early age, others after a long wait. Scientists have proved that genes are responsible for these early differences. But people assume that as children get older and spend more time under their parents’ influence, the effect of genes declines. They are wrong.

For a century or more, we have understood that intelligence is largely inherited, though even today some mistakenly rail against the idea and say that nurture, not nature, is all. Now we know that much of our personality, too, is inherited and that many social attitudes have some degree of genetic basis, including our involvement in crime and some psychiatric illnesses. Some things do result entirely from environmental influences, such as whether you follow the Red Sox or the Yankees (though I suspect that Yankee fans have a genetic defect). But beyond routine tastes, almost everything has some genetic basis. And that includes politics.


http://www.city-jour...9/19_1_dna.html

[stocks]

The Five Laws of Behavioral Genetics 

 

Identical twins raised apart will be similar – and usually highly similar in every conceivable measurement  

 

The effect of being raised in the same family is smaller than the effect of the genes.

 

A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

 

Simplistic notions of a “single gene causes X” are wrong, because in reality there are a plethora of genetic variants at play in a given behavioral trait.  

 

Whenever there is an association between two phenotypes (such as poverty and crime), there will be a genetic association driving both.

 

-This essentially strikes at the heart of modern social science (and for that matter, medical science), which assumes, wrongly, that association between social and/or behavioral factors is an indication that one causes the other. In reality, genetic forces cause both. 

 

-Indeed, we see this with health and lifestyle: people who exercise more have fewer/later health problems and live longer, so naturally conventional wisdom interprets this to mean that exercise leads to health and longer life, when in reality healthy people are driven to exercise and have better health due to their genes. 

 

 http://www.unz.com/j...ioral-genetics/

 

 

 

 

 

[MaryAM]

They have known about the correlation between psychiatric disease and Chromosome 22 deletion for decades.   Didn't want to pursue the studies because defining psychiatric problems as a "disease" instead of a "disorder" would put a number of psychobabble PhD's out of business as diagnosed people would have to see medical doctors instead of someone who could "counsel" them out of their symptoms.   Politics and medicine should not be allowed.   

[Rogerdodger]

I love the nature-vs-nurture debate. The twins studies sure changed my mind about how genetics control so much. My grandson hardly ever saw his father but danced exactly as did his father. 

I have a gay friend who tells about being "fabulous" as a very young boy and even though his father tried to kill him for his effeminate ways , he's still fabulous!

Interesting stuff for sure.