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February 26, 2019

A blueprint in our genes for behavior?

Filed under: Eugenics,Genetics,Personality,Psychology — Razib Khan @ 4:44 pm

Since the emergence of the field of genetics over a century ago the question of “nature vs. nurture” has loomed large over the field when it comes to the nature of “human nature.” The very term “human nature” is a tell as to its origins and early connotations: the early idea was that we are “born that way.” Society was seen to have a hereditary basis, as was your own individual life outcome.

It is true that in the early decades of genetics, researchers were preoccupied with fruit flies, pedigrees, and equations. But genetics was not alone on the scene. Eugenics, a social and cultural movement which presented itself as an application of hereditary science to improve the human race, developed in the same decades to great public aclaim. One of the founders of the field of statistical genetics, Francis Galton, was also the founder of eugenics!

Though the history books tell us about the history of eugenics with the shocking culmination of the horrors Nazi Germany, the fact is that the nation which arguably took up eugenics most enthusiastically in the decades before World War II was the United States of America! This was a period when socialists such as H. G. Wells, and conservatives such as Winston Churchill, both supported eugenics. The German Nazis modeled many of their policies and laws on American precedents.

It is in the context of this history that the branch of psychology dealing in heritable individual differences, behavior genetics, slipped into the shadows in the decades after the defeat of the Nazis. The nature of heritability of behavioral characteristics was somewhat taboo because they had been the subject of fascination by eugenicists. Genetics generally restricted itself to healing terrible diseases. When it comes to other aspects of mind and body it receded. For example, Freudianism and Behaviorism were more common perspectives brought to bear on individual differences and outcomes in psychology. Though these perspectives did not reject biological inheritance as such, they focused on environmental inputs and outputs.

Schizophrenia was seen as a disease of upbringing or environmental exposure. Not one of genetic transmission from parent to offspring (today we know that schizophrenia is 80% heritable!).

This situation began to change with the emergence of a field of cognitive science which held that some aspects of psychology were innate, such Noam Chomsky’s theory of universal grammar, which implied a biological underpinning for our facility with language. And, just as some psychologists were exploring the inherited bases of our universal behaviors and aptitudes, others began to look more closely at differences. Human variation.

The reemergence of behavior genetics, the study of individual differences, and the attempt to infer both the environmental and genetic components of various outcomes evolved in the context of large longitudinal studies of twins and their siblings. The logic here is simple: the correlation in a characteristic such as height between identical twins is nearly perfect. For siblings (and fraternal twins), there is a correlation, but it is far weaker because sibling relatedness is only 50%. If the correlation on a behavioral trait, such as the likelihood of schizophrenia, is correspondingly greater between identical twins than between their siblings, then it is highly heritable. Genes play a large role in the trait’s expression. In contrast, if there is no difference between twins and how siblings correlate on a trait, then that suggests that there is not much of a genetic basis to the characteristic. Recall, identical twins by definition are more genetically related than two siblings.

There are of course many theoretical objections to twin studies (e.g., perhaps parents treat twins more similarly than they do siblings), and the statistical abstruseness of behavior genetics means that its implications and findings did not get broad coverage as the field matured in the late 20th century. Despite several decades of research, by the year 2000, it is likely most people were not aware of the substantial heritability of many behavioral and psychological characteristics, from personality disposition to mental illness.

The last few decades have changed this, in part because the new science of genomics, which looks beyond statistical correlations of characteristics to raw DNA sequence, has begun to merge with behavior genetics. Because psychological characteristics were almost always defined by the small effect of many numerous genes classical genetics did not have the power to locate any genes that were involved in psychological variation. But with massive sample sizes of as much as a million and hundreds of thousands of genetic positions, new research is now confirming the statistical work from twin studies that many psychological characteristics are substantially heritable.

Illumina Sequencer

The study of human nature and our differences and the possible genetic causes of them began with a tragedy and a travesty. Eugenics marred the legacy of many early geneticists, and its application in the United States and Nazi Germany were crimes against humanity. But as the 21st century proceeds the study of human psychology and its genetic basis is now becoming a true science. Able to describe, as well as predict.

But, it turns out its powers of prediction are quite modest, far less than any eugenicist would have foreseen or dreamt of. The truth is a genetic test can give you only a small improvement on your odds of knowing the likely track of your life. And perhaps that is for the best.

A blueprint in our genes for behavior? was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

November 11, 2012

Eugenics, the 100 year cycle

Filed under: Eugenics,Genetics — Razib Khan @ 11:50 pm

The Chronicle of Higher Education has a piece out by Nathaniel Comfort, The Eugenic Impulse. I would just like to offer that to a great extent we already live in the second age of eugenics. The high frequency of abortions of fetuses which come back positive for Down syndrome is well known. But it seems possible that we’ll be able to reduce the frequency of many Mendelian diseases as well. Basically those ailments which are due to a major mutation of large effect and high penetrance (i.e., you have the mutation, you have the disease).

A major goal which we’re very far from though is the ability to select for quantitative traits. There are technical hurdles, both tactical and strategic, here. The major issue is that there are simply too many variants for one to be able to select a ‘perfect’ genetic profile. Those who’ve talked to me know my response in this domain: select for low mutational load. High coverage fetal whole genome sequencing would do that. The marketing pitch for this writes itself: imagine you, but bright of mind, and beautiful of face!

July 10, 2012

Toward healthier gestations

Neuroskeptic has a post up, The Coming Age of Fetal Genomics:

So they don’t. Instead, they buy a $100 test kit, they each provide a small blood sample and send it off to one of the companies offering fetal genome testing. At the testing lab, they can separate out the mother’s DNA from that of the fetus, both of which are present in the mother’s blood. By comparing the fetal genome to the mother’s and father’s, it’s easy to spot de novo mutations. If a certain gene doesn’t match either the mother or the father’s sequence, it’s mutated.

A few days later the results are back. There are several mismatches detected. Most are benign – they’re not predicted to have any biological effects. But there’s one, a deletion of a few thousand bases in a gene involved in brain development. This deletion is predicted to raise the risk of epilepsy and autism from 1% to 10% apiece. The parents now have a decision to make. The mutation is a one off, it’s not inherited. If they conceive again… roll the dice again… and it’ll be gone. Do they terminate?

Like the adverts say, “Some people disagree with this, but we say there’s only one ...

January 2, 2012

Euthanasia, not eugenics

Filed under: Bioethics,Eugenics,Euthanasia — Razib Khan @ 11:08 pm

A comment below clarified my thinking in one particular area: is widespread genetic screening going to result in a reconsidering of the idea of ‘engineering’ society? I realize now that in a comparative scenario this is ridiculous. The majority of healthcare expenditure is near the end of life, not the beginning. In 17 years the last of the Baby Boomers will turn 65. The looming costs are rather straightforward. And it’s not just an issue in the United States, the whole worlds is going gray.


How do we handle this sort of sociological challenge? One solution lies in increased economic productivity through innovation. This is great if you can get it. But another was option is obviously something like a milquetoast form of Logan’s Run.* Governor Dick Lamm was reputed to have said “we have a duty to die.” But not to be churlish, I observe that at 77 years of age now Lamm himself continues to be active and full of life (he made the comments when he was 50).

I’ve also been thinking about this issue because of a radio series on learning to live with “early onset” Alzheimer’s. Upon further reflection I realize that I don’t think I would want to “learn to live” with such a disease. Yes, such things are easy to say now. But perhaps it is best that we start to consider these issues as early as possible, both individually, and as a society. At the end of the day many of us would say that the point of living is to live a good life, not to just live.

* The option of allowing in large numbers of immigrants is a short term solution, the source nations for migration are themselves aging.

August 24, 2011

Eugenics as a luxury of the affluent

Filed under: Eugenics,Futurism,Health — Razib Khan @ 12:12 pm

In the comments below Jason says in regards to the connection between eugenics and genocide and the “slippery slope”:

In your current comfortable first world circumstances, you are right the slope is perhaps not that slippery. I hope you are never tested in a less comfortable setting as then I think you might find it can be pretty slippery after all.

A reference to the interlocutor’s status as a citizen of the comfortable First World (which itself is a somewhat archaic term by now I think) seems de rigueur in many arguments. And I think many people will find it plausible that someone in an affluent consumer society would be blind to the “dark side” of eugenics, and how it could lead to genocide. But I think this plausibility is entirely superficial, and collapses upon closer inspection. Rather, it is I believe in “First World” and advanced nations where the likelihood of the ubiquity of eugenics and possible genocide predicated on systematic eugenics is going to be the most probable outcome.

There is a large general issue at the root of this confusion, the implicit progressive “Whiggishness” in our sensibilities, which derives in part from the power of science to advance in ...

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