More importantly, heritability estimates should be discarded. Their only practical purpose is to predict the results of a selective breeding program under controlled conditions. For any other purpose, heritability estimates are misleading and meaningless. A condition may ot may not be influenced by genetic factors, but “heritability” does not exist.
You are mistaken about DZA twins not being the MISTRA control group. The MISTRA compared MZ twins reared together (MZTs) vs. MZ twins reared apart (MZAs) twins only for the purpose of assessing the role of the family environment. In his 2023 reply to my article, lead investigator T. Bouchard did not dispute my claim that reared-part DZ twins (DZAs) were the official MISTRA control group. Here is a 1986 publication where Bouchard et al. said that DZAs were the MISTRA control group:
Bouchard et al., (1986), “Development in Twins Reared Apart: A Test of the Chronogenetic Hypothesis,” in A. Demirjian (Ed.), Human Growth: A Multidisciplinary Review (pp. 299-310), London: Taylor & Francis. On page 300, they wrote:
“Our study is the first to have included a control group of dizygotic twins reared apart
(DZA). … DZA twins allow us to test the two most common competing hypotheses
proposed as alternatives to the genetic hypothesis as an explanation of the similarity
between MZA twins: placement bias and recruitment bias.”
See also page 12 of Nancy Segal’s 2012 book on the MISTRA, “Born Together: Reared Apart,” where she wrote:
“The MISTRA was … the first study of its kind to include both MZA and DZA twin pairs.
Bouchard’s decision to use DZA twins as controls was made in a very early [1979] memo
to the ‘Twin Research Team.’ This was an important methodological improvement over past
projects”
Or how about this thought experiment I decided to leave out of the article: What if all ten Galvin boys had been adopted away at birth and placed immediately with ten different randomly selected adoptive families. How many of them would have developed psychosis? My guess is zero.
Thanks for your interesting comments. Just for the record, I didn’t directly say that “Rosenthal’s 1968 negative-result (failure to reject the null hypothesis) study discredited the idea that genetics ‘created the disease.’” One study cannot do that. I was saying that the author of Hidden Valley Road could have reached that conclusion if he had read the study carefully, and if he had read what critics had to say about the study. He did neither of those, and he reached the opposite conclusion–that Rosenthal’s research showed that nature won the schizophrenia/psychosis nature-nurture argument.
Hello. The pooled identical (MZ) concordance rate for schizophrenia is less than 25% in the better-performed studies, which can be explained by non-genetic influences. In the most recent study the MZ rate was 14.8%. There is no scientifically valid evidence that genes have anything to do with schizophrenia/psychosis. That doesn’t prove that genes play no role, but only that currently there is no evidence that they do play a role.
Also worth noting that most psychiatric genetic researchers concede the point that “running in the family” does not prove anything about genetics. For example, in the 2020 second edition of “How Genes Influence Behavior,” top genetic researchers Jonathan Flint and Kenneth Kendler recognized that a condition running in the family can be caused by the common environments families share. They wrote:
“In human families, relatives can be similar because they share environments or because they share genes, or both. Relatives share all kinds of environments. They live in the same neighborhoods, often attend religious services together, eat a similar diet, are exposed to the same level of harmony or conflict in their home, and might all live close to an industrial plant that pumps out pollution into the air or water. All of these reasons and more could explain the resemblance among members of the same family.”
On this single point–that family studies cannot be interpreted genetically–psychiatric geneticists and the field’s critics are in agreement.
Responding to your question, “I’d like to know why they would share religion. Is this because they are adopted through religiously-affiliated adoption agencies??”
I was not thinking so much about religiously-affiliated adoption agencies as I was about countries and cultures with a dominant religion. For example, it is likely that birthparents and their adopted-away offspring in Spain grow up with the teachings of the Catholic religion, which influences people’s beliefs and behaviors. This is an example of a major non-genetic behavioral influence shared by birthparents and adoptees. They may not have grown up together in the same family, but they grew up and live together in similar non-familial social environments. Another example would be adoptions made within religious communities such as the Pennsylvania Amish, where we would expect to see much behavioral resemblance for non-genetic reasons.
In the article, I addressed the “blank slate” strawman that you and others use to try to discredit critics of genetic research. It would be better if you could come up with some arguments against those of us who say that behavioral genetic research, including twin research, is massively flawed.
Thanks for your reply. The main thing to keep in mind is that, regardless of what one thinks about twin studies, heritability percentages do not estimate “how much” genes influence a behavioral characteristic, or how changeable it is. “Heritability” is not the same as “inherited.” The best course of action would be to ignore heritability estimates entirely, since the main thing they do is mislead people. Please take a look at this article if you like:
Thanks. I am really glad that my articles have helped you, and that they will help you and others argue against dominant yet false positions.
For those interested, I just posted some information (linked below) on how the identical (MZ) twins found in so-called “reared-apart” twin studies were not “reared apart” in the way that most people understand this term. In fact, most twin pairs were only partially reared apart.
Until the error is fixed, you should aware that, in the third paragraph, everything beginning with “believing very strongly in nurture…” until the end of the paragraph is either a quotation from an interview with filmmaker Tim Wardle, or my comments about what he said. It should all be part of endnote #1, and should not appear in the main body of my article.
The portion that currently (6-21-2019, 4:40 pm EST) reads “…believing very strongly in nurture. I was shocked to discover just how influential DNA is. The idea that you could make decisions in your life for reasons that hinge on your ancestors—that you can’t fight and do unconsciously—it’s freaky” is from an interview with Wardle. These are his words, not mine.
Hello. The title does not say or imply that genes have “nothing to do with mental illness.” What it does say/imply is that twin studies fail to provide scientifically acceptable evidence that genes play a role. Psychiatric conditions and behavior in general can “run in families” due to the shared environments experienced by family members. Most genetic researchers now recognize this.
Thank you Marie. You make some good points. Nancy Segal’s book received mostly positive reviews, and won a prize from the American Psychological Association. In my linked articles, however, I show that her arguments do not hold up. On the issue of not allowing the raw data to be examined, I concluded in the (linked) full version of the article that when social and behavioral science investigators refuse to make their raw data available for inspection and analysis by qualified reviewers—especially when the study’s results have important social policy implications—we must automatically reject their findings when they are based on samples taken from rare populations that cannot be independently reproduced, such as reared-apart twins. The MISTRA researchers did not allow independent review of their raw data, and then asked us to accept their claim that genetic factors play a major role in causing behavioral differences among billions of human beings—past, present, and future— on the basis of how a few hundred abandoned twins performed on psychological tests.
I do not focus on epigenetics because, as I wrote in an earlier comment, in searching for and understanding the causes of psychosis and emotional distress, we must look outside of the body, not inside. Internal processes, even if relevant, distract from addressing the outside causes. To better understand this point, just think of any type of mistreatment or oppression that people experience or suffer. As one example, if a child is bullied at school, we must focus on stopping the bullying and creating a bully-free school environment. Studying the bullied child’s brain and genes would be a distraction from making the necessary changes in the environment. There are countless other examples.
Thanks Madmom. I did try to make the article as understandable as possible, so thanks for confirming that it came through that way. I like the proposal you presented in the final paragraph.
Francesca. This is true, and confirmation bias should therefore be much more recognized and taken into account throughout science when evaluating research findings.
Hello Bonnie. Thanks for your reply and the references to your work. With all due respect, I still maintain that in searching for and understanding the causes of psychosis and emotional distress, we must look outside of the body, not inside.
I was referring to what genetic researchers and mainstream psychiatry refer to as a “severe” form of schizophrenia based on what they see as severe symptoms. I did not imply that there is a genetic basis to “severe symptoms.” What I have argued since 1998 is that there is no scientifically acceptable evidence that any form of “schizophrenia” is caused by disordered genes.
It actually is true that most “scientists accept that there is a gene involved in this.” I have attempted to show that there is little evidence supporting this position.
From the standpoint of the people who do these studies, examples of “severe symptoms” include auditory hallucinations, delusions, and “thought broadcasting,” as opposed to “milder symptoms” such as social withdrawal and flattened affect.
I don’t think schizophrenia rates increased much if at all, but based on what I have read they didn’t decrease either. Please let me know if you have additional information on this point, other than the Torrey article that addressed this issue.
I doubt that prenatal environments play much of a role, but I am certainly open to other ideas. For the most part, I focus on the importance of postnatal environments.
Aside from the degree of previous contact, even in the very rare cases where pairs are separated at birth and meet for the first time when studied, their similar behavior is still heavily influenced by the cultural/environmental cohort effects I mentioned.
The researchers’ 50% heritability calculation is meaningless for three main reasons: 1) The MISTRA researchers falsely assumed at all MZA behavioral resemblance was caused by genetics; 2) Heritability estimates do not show “how much” genes contribute to a trait, and should therefore be abandoned entirely in the social and behavioral sciences; 3) Most pairs were only partially reared apart.
Relating to your point about the data being “locked in a vault somewhere,” this seems to be the case. I discuss this in detail in my book, and briefly in my 12/15/2014 MIA blog.
Steve’s comments captured what I was thinking and wanting to write. Outstanding analysis and outstanding writing. I greatly look forward to your future postings.
Thanks for your reply. Since the topic was an examination of the alleged evidence that schizophrenia is caused by disordered genes, I mentioned the issues relating to birthrates, and the validity of the “schizophrenia” concept, only in passing. But of course, they are important issues in their own right, and have been covered very well by others. To clarify, I did not use the term “schizophrenic” or “schizophrenics” in the article. When these terms do appear, they are always found in quotations taken from other writers.
Jinxer. Current genetic theories are based on genetic interpretations of the data, not on anecdotes, but the anecdotes weigh heavily in the public imagination. But they shouldn’t, since they prove no more about genetics than stories about the powers of astrology do about astrology, and so on. This is all in my book The Gene Illusion, and will be in a future MIA posting. My next posting will be about genetic studies of schizophrenia.
These are very good questions. In my most recent book, “The Trouble with Twin Studies,” as well as my 2004 book “The Gene Illusion,” I explained why these stories about supposedly reared-apart twin pairs do not prove or even suggest anything about genetic influences on behavior. I am hoping to post something in my MIA blog on this topic by mid-January. Please look for it. Some of the points I raised in my earlier MIA blog on reared-apart twin studies relate to individual pairs as well.
Thank you for your important article, and for writing about about how mainstream psychiatry and psychology depoliticize and decontextualize human behavior, and seek to maintain the status quo. These are very important points.
I agree with you, and I have pointed out in the past that genetically oriented researchers usually overlook countless real word examples running counter to their claims. Behavioral geneticists frequently refer to twin studies as “natural experiments,” but they overlook many other natural experiments that point to the importance of environment, such as the one you mention in relation to Australia and the crime rate.
Thanks. You make some really good points, and we must always keep in mind that the people/corporations/governments funding this research have an interest in diverting our attention from the environmental “controllable variables” you mention, in addition to many others.
For a number of reasons, individual stories of the supposed similarities of reunited reared-apart MZ pairs prove nothing about genetics. Dissimilar pairs, of which there are many, are not interesting news stories and do not support the typically pro-genetic orientation of twin researchers who conduct reared-apart twin studies.
Eugenic ideas and practices were widespread in Finland and other Scandinavian countries for much of the 20th century. A well researched academic book on the topic of Scandinavian eugenics is:
Broberg, G., & Roll-Hansen, N. (Eds.). (1996). Eugenics and the Welfare State: Sterilization policy in Denmark, Sweden, Norway, and Finland. East Lansing, MI: Michigan State University Press.
Thanks. Black’s book is excellent. I would also highly recommend Allan Chase’s classic 1977 book on eugenics, “The Legacy of Malthus.” Simply a must read.
The word “eugenics” stopped being used openly in the 1960s and early 1970s. It was still used frequently in a positive sense until then, when journals such as “Eugenics Quarterly” became “Social Biology” only in 1968. Between 1944 and 1965, the American Journal of Psychiatry had an annual “Review of Psychiatric Progress,” with a “Heredity and Eugenics” section authored by Franz J. Kallmann.
Hello. Psychiatric researchers have been looking for faulty brains and faulty genes for decades, and have found none, as the APA officially admitted in 2013 (see below). They have found nothing, yet they continue searching while largely ignoring environmental causes because they mistakenly see psychiatric disorders as “highly heritable brain diseases.”
There are many environmental causes of dysfunction and distress other than “trauma.” The hand cleaning compulsion you mention is caused by people believing that they will contract a dangerous disease if they don’t wash their hands repeatedly. So it is necessary to help them question this belief, and to understand this belief in the context of their history and the social environment they grew up in and continue to experience. As Szasz pointed out many times, if a brain disease is discovered, the condition ceases to be a psychiatric disorder, and becomes a neurological disorder.
It doesn’t appear that you read the entire article. Towards the end, I wrote:
“In their 2013 work Mad Science: Psychiatric Coercion, Diagnosis, and Drugs, Stuart Kirk, Tomy Gomory, and David Cohen showed that there are serious reliability and validity problems in psychiatry, suggesting that research is impaired when it relies on the DSM to diagnose people with similar problems. A lack of reliability and validity has important implications for psychiatric genetic family, twin, and adoption studies—and accompanying heritability estimates—because many people diagnosed in these studies may not actually ‘have’ the condition at all.”
In any case, the article was about the claims of people who do see these categories and valid, reliable, and “heritable.” This was not the place to go into an elaborate debunking of the of psychiatric disorder (“mental illness”) concept, which many other MIA authors have done very well, and for the most part I agree with them on this point and have said so in previous books and articles.
Thanks Norman. To put it simply, to identify the causes of emotional suffering and behaviors that fall into DSM categories, we must look outside of the brain and body.
I agree that psychological characteristics are difficult to define, yet all claims about genetic influences on them assume that they are valid quantifiable concepts.
The conclusion that nature and nurture are “tied” is based on the claim that most behavioral traits are 50 heritable. In my next posting, I plan to look at the misleading “heritability” concept itself.
Hi. My first article on reared-apart twin studies appeared in 2001. It can be downloaded from the Publications page at my website. I also covered the topic in Chapter 4 of my 2004 book The Gene Illusion.
But by far the most in-depth analysis of the many problems and biases in reared-apart twin research is found in my new book, The Trouble with Twin Studies: A Reassessment of Twin Research in the Social and Behavioral Sciences. For more information on this book, including a link to chapter summaries, please see http://www.jayjoseph.net/the_trouble_with_twin_studies
I am thinking of posting on this topic in the near future.
You make some interesting points about twins, and researchers do tend to overlook many obviously problematic aspects of twin research. I think you will like my upcoming book, where I cover many of the central concepts and methods of behavioral genetics from a critical perspective.
Hi. Like all such claims since the 1960s, this one is unlikely to hold up. An additional point is that, in the unlikely case that the results are confirmed, this would seem to invalidate every study ever done that used the singular concept of “schizophrenia,” since what was previously viewed as one disorder was actually eight different disorders.
As far as C. Robert Cloninger is concerned, he has made subsequently non-replicated schizophrenia “gene discovery” claims in the past. For example, in 2002 he published an article in the leading scientific journal PNAS, where he claimed, on the basis of three then-recently published studies, “For the first time, specific genes have been discovered that influence susceptibility to schizophrenia.”
(see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC129675/ )
I am glad that you are interested in further dialogue, and the dialogue of course would be open to various opinions. But I don’t think it is necessary for anyone to “give a little” when it relates to what a person believes to be true. Much better, in my view, would for all sides to state their case and leave it to others to decide who is right. I am glad that you are criticizing heritability estimates, which as you know critics have been doing for many years.
Regarding possible gene findings, I have stated that, given the history, all gene finding claims for behavioral traits and psychiatric disorders should be considered false positive until proven otherwise. But for me, the issue is really much more about approach . Even if some genes are eventually found for behavior, IQ, or psychiatric disorders, which I doubt will happen (in part because they would have been found by now), genetic approaches would remain a distraction and would continue to divert attention from the need to improve the environmental conditions that play a huge role in all aspects of human behavior, abilities, and physical health.
The behavioral genetic approach, in addition to being based on faulty science in my view, diverts attention from and actually helps prevent environmental interventions to improve the human condition. It is true that BG researchers frequently mention that the environment is important, but the BG approach leads people to think mainly in terms of genetics. And twin studies are one of the main reasons they continue to think in this way. But yes, more public discussion would be great. Finding areas of agreement on some points is fine, as long as the agreement is genuine, as I am sure you would agree.
First, I would like to say that I am pleased that you responded and that this dialogue is occurring. I make a point in my writing to represent everything truthfully and accurately, so I appreciate that you called my attention to this. However, I reread your 2011 “Still Missing” article and I must stand by my original statement, based on what I read there. That being said, the main question in light of the failure to uncover genes for behavioral traits and disorders, more than 13 years after the sequencing of the human genome, is the question of the validity of twin research. You and I clearly have different opinions about twin studies and the validity of the MZ-DZ “equal environment assumption,” upon which all genetic interpretations of twin method data are based. You might agree with me that there should be a greater level of public discussion about the value of twin research, with all sides of the issue participating in this discussion. I would welcome a collaboration with you on bringing this issue to greater public awareness, if you are interested.
Thanks Ted for reminding everyone of the terrible consequences that can results from being falsely seen as carrying, as they called it in those days, the “hereditary taint” of schizophrenia.
I discussed the equal environment assumption of the twin method in both of my books, and more in-depth in an article that came out this year in The Journal of Mind and Behavior (2013, Vol.34, pp. 1-40). I also have some publications on ADHD and genetics, including a 2009 chapter and a 2000 article. All of these can be downloaded from my website at http://www.jayjoseph.net/publications
Hi, the method you mentioned to calculate twin concordance is still widely used. It is called the “probandwise” concordance rate method. The probandwise method of double counting does not create concordance where there is none, but it serves to inflate concordance rates calculated as a simple percentage, which is known as the “pairwise” rate.
Since you mentioned the German psychiatric geneticist Ernst Rüdin, you may be interested in an article about him that I co-wrote that has recently been published. The URL is http://www.ncbi.nlm.nih.gov/pubmed/23180223
Thanks, Keith. I appreciate that.
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More importantly, heritability estimates should be discarded. Their only practical purpose is to predict the results of a selective breeding program under controlled conditions. For any other purpose, heritability estimates are misleading and meaningless. A condition may ot may not be influenced by genetic factors, but “heritability” does not exist.
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You are mistaken about DZA twins not being the MISTRA control group. The MISTRA compared MZ twins reared together (MZTs) vs. MZ twins reared apart (MZAs) twins only for the purpose of assessing the role of the family environment. In his 2023 reply to my article, lead investigator T. Bouchard did not dispute my claim that reared-part DZ twins (DZAs) were the official MISTRA control group. Here is a 1986 publication where Bouchard et al. said that DZAs were the MISTRA control group:
Bouchard et al., (1986), “Development in Twins Reared Apart: A Test of the Chronogenetic Hypothesis,” in A. Demirjian (Ed.), Human Growth: A Multidisciplinary Review (pp. 299-310), London: Taylor & Francis. On page 300, they wrote:
“Our study is the first to have included a control group of dizygotic twins reared apart
(DZA). … DZA twins allow us to test the two most common competing hypotheses
proposed as alternatives to the genetic hypothesis as an explanation of the similarity
between MZA twins: placement bias and recruitment bias.”
See also page 12 of Nancy Segal’s 2012 book on the MISTRA, “Born Together: Reared Apart,” where she wrote:
“The MISTRA was … the first study of its kind to include both MZA and DZA twin pairs.
Bouchard’s decision to use DZA twins as controls was made in a very early [1979] memo
to the ‘Twin Research Team.’ This was an important methodological improvement over past
projects”
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Or how about this thought experiment I decided to leave out of the article: What if all ten Galvin boys had been adopted away at birth and placed immediately with ten different randomly selected adoptive families. How many of them would have developed psychosis? My guess is zero.
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Thanks Steve. I always appreciate your support.
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Thanks Patrick. I would be happy to hear from Robert Kolker if he thinks anything I wrote in the article is wrong.
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Thanks for your interesting comments. Just for the record, I didn’t directly say that “Rosenthal’s 1968 negative-result (failure to reject the null hypothesis) study discredited the idea that genetics ‘created the disease.’” One study cannot do that. I was saying that the author of Hidden Valley Road could have reached that conclusion if he had read the study carefully, and if he had read what critics had to say about the study. He did neither of those, and he reached the opposite conclusion–that Rosenthal’s research showed that nature won the schizophrenia/psychosis nature-nurture argument.
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Thank you Adam.
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I will be happy to try to answer his questions.
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Hello. The pooled identical (MZ) concordance rate for schizophrenia is less than 25% in the better-performed studies, which can be explained by non-genetic influences. In the most recent study the MZ rate was 14.8%. There is no scientifically valid evidence that genes have anything to do with schizophrenia/psychosis. That doesn’t prove that genes play no role, but only that currently there is no evidence that they do play a role.
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Thanks. I hope you like it.
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Thanks. I hope you like it.
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Also worth noting that most psychiatric genetic researchers concede the point that “running in the family” does not prove anything about genetics. For example, in the 2020 second edition of “How Genes Influence Behavior,” top genetic researchers Jonathan Flint and Kenneth Kendler recognized that a condition running in the family can be caused by the common environments families share. They wrote:
“In human families, relatives can be similar because they share environments or because they share genes, or both. Relatives share all kinds of environments. They live in the same neighborhoods, often attend religious services together, eat a similar diet, are exposed to the same level of harmony or conflict in their home, and might all live close to an industrial plant that pumps out pollution into the air or water. All of these reasons and more could explain the resemblance among members of the same family.”
On this single point–that family studies cannot be interpreted genetically–psychiatric geneticists and the field’s critics are in agreement.
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Most likely, insurance companies hoping to reduce claims payouts would finance “weak bone disorder” research.
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Thanks. But the evidence in favor of an inherited propensity for schizophrenia/psychosis simply is not there.
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Thanks Pat. I quoted from your book on psychiatric genetics in ch 5.
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Thanks Richard.
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Thanks John. I am a big admirer of you and the work you are doing.
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Thanks. My book about schizophrenia and genetics (or lack thereof) will be published in 2023.
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Thanks Pat. I have a discussion of Kolker’s book in my own book on schizophrenia and genetics, coming out next year.
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Responding to your question, “I’d like to know why they would share religion. Is this because they are adopted through religiously-affiliated adoption agencies??”
I was not thinking so much about religiously-affiliated adoption agencies as I was about countries and cultures with a dominant religion. For example, it is likely that birthparents and their adopted-away offspring in Spain grow up with the teachings of the Catholic religion, which influences people’s beliefs and behaviors. This is an example of a major non-genetic behavioral influence shared by birthparents and adoptees. They may not have grown up together in the same family, but they grew up and live together in similar non-familial social environments. Another example would be adoptions made within religious communities such as the Pennsylvania Amish, where we would expect to see much behavioral resemblance for non-genetic reasons.
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Thanks. I really appreciate your support.
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In the article, I addressed the “blank slate” strawman that you and others use to try to discredit critics of genetic research. It would be better if you could come up with some arguments against those of us who say that behavioral genetic research, including twin research, is massively flawed.
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Thank you Daniel. I really admire your work.
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Thanks Steve. I will give your idea some thought.
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Thanks for your reply. The main thing to keep in mind is that, regardless of what one thinks about twin studies, heritability percentages do not estimate “how much” genes influence a behavioral characteristic, or how changeable it is. “Heritability” is not the same as “inherited.” The best course of action would be to ignore heritability estimates entirely, since the main thing they do is mislead people. Please take a look at this article if you like:
http://pzacad.pitzer.edu/~dmoore/publications/2016_moore–shenk_the-herit.pdf
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Thank you.
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Thank you Steve and Caroline.
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Good point Steve. Thanks
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Thanks. I am really glad that my articles have helped you, and that they will help you and others argue against dominant yet false positions.
For those interested, I just posted some information (linked below) on how the identical (MZ) twins found in so-called “reared-apart” twin studies were not “reared apart” in the way that most people understand this term. In fact, most twin pairs were only partially reared apart.
http://jayjoseph.net/yahoo_site_admin/assets/docs/Reared-Apart_Twin_Study_Tables.361115309.pdf
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Thanks for your support.
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Thank you Judi. I appreciate your supportive comment.
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Thank you.
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Thank you, Steve.
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Thank you, Lawrence. I appreciate that.
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Thank you for your interesting comments. You are right that one of the triplets had been diagnosed/labeled with bipolar disorder. I should have mentioned this, and the fact that the other two triplets were not diagnosed/labeled bipolar is not consistent with genetic theories. In chapter 10 of my book “The Missing Gene,” I attempted to debunk genetic theories of bipolar disorder. Also see https://www.madinamerica.com/2015/12/ernst-rudins-unpublished-family-study-of-manic-depressive-insanity-and-the-genetics-of-of-bipolar-disorder/
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Dear Readers,
Until the error is fixed, you should aware that, in the third paragraph, everything beginning with “believing very strongly in nurture…” until the end of the paragraph is either a quotation from an interview with filmmaker Tim Wardle, or my comments about what he said. It should all be part of endnote #1, and should not appear in the main body of my article.
The portion that currently (6-21-2019, 4:40 pm EST) reads “…believing very strongly in nurture. I was shocked to discover just how influential DNA is. The idea that you could make decisions in your life for reasons that hinge on your ancestors—that you can’t fight and do unconsciously—it’s freaky” is from an interview with Wardle. These are his words, not mine.
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Thank you Miranda. I just put in a request to have that fixed.
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Thank you Steve.
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Hello. The title does not say or imply that genes have “nothing to do with mental illness.” What it does say/imply is that twin studies fail to provide scientifically acceptable evidence that genes play a role. Psychiatric conditions and behavior in general can “run in families” due to the shared environments experienced by family members. Most genetic researchers now recognize this.
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Thanks for your comments.
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Lawrence,
Thank you. I really appreciate your support.
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Thank you Marie. You make some good points. Nancy Segal’s book received mostly positive reviews, and won a prize from the American Psychological Association. In my linked articles, however, I show that her arguments do not hold up. On the issue of not allowing the raw data to be examined, I concluded in the (linked) full version of the article that when social and behavioral science investigators refuse to make their raw data available for inspection and analysis by qualified reviewers—especially when the study’s results have important social policy implications—we must automatically reject their findings when they are based on samples taken from rare populations that cannot be independently reproduced, such as reared-apart twins. The MISTRA researchers did not allow independent review of their raw data, and then asked us to accept their claim that genetic factors play a major role in causing behavioral differences among billions of human beings—past, present, and future— on the basis of how a few hundred abandoned twins performed on psychological tests.
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Thanks Steve.
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Thanks to Gary, Steve, and others for your support.
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Hello Greg.
I do not focus on epigenetics because, as I wrote in an earlier comment, in searching for and understanding the causes of psychosis and emotional distress, we must look outside of the body, not inside. Internal processes, even if relevant, distract from addressing the outside causes. To better understand this point, just think of any type of mistreatment or oppression that people experience or suffer. As one example, if a child is bullied at school, we must focus on stopping the bullying and creating a bully-free school environment. Studying the bullied child’s brain and genes would be a distraction from making the necessary changes in the environment. There are countless other examples.
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Thank you Richard.
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Thanks Madmom. I did try to make the article as understandable as possible, so thanks for confirming that it came through that way. I like the proposal you presented in the final paragraph.
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Thank you very much.
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Francesca. This is true, and confirmation bias should therefore be much more recognized and taken into account throughout science when evaluating research findings.
Steve, thanks for your comments.
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Hello Bonnie. Thanks for your reply and the references to your work. With all due respect, I still maintain that in searching for and understanding the causes of psychosis and emotional distress, we must look outside of the body, not inside.
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Thanks Eric. And the story is similar for all other major psychiatric disorders.
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Thanks for the nice comments by Igor and others.
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Rossa,
I was referring to what genetic researchers and mainstream psychiatry refer to as a “severe” form of schizophrenia based on what they see as severe symptoms. I did not imply that there is a genetic basis to “severe symptoms.” What I have argued since 1998 is that there is no scientifically acceptable evidence that any form of “schizophrenia” is caused by disordered genes.
It actually is true that most “scientists accept that there is a gene involved in this.” I have attempted to show that there is little evidence supporting this position.
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Hello Rossa,
From the standpoint of the people who do these studies, examples of “severe symptoms” include auditory hallucinations, delusions, and “thought broadcasting,” as opposed to “milder symptoms” such as social withdrawal and flattened affect.
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Thanks, Frank. The idea is ludicrous for sure, but it has been going on for a long time.
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Thank you, Steve.
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To BPDT: See also page 11 of my 2006 book “The Missing Gene,” and my 6/24/15 MIA blog on heritabilty (and my response to Paula Caplan’s comments).
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To BPDT,
Take a look at page 157 of the 2004 Algora edition of “The Gene Illusion,” and pp. 189-198 of my 2015 book “The Trouble with Twin Studies.”
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I have made that point about schizophrenia, and other DSM diagnoses, in many publications.
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I don’t think schizophrenia rates increased much if at all, but based on what I have read they didn’t decrease either. Please let me know if you have additional information on this point, other than the Torrey article that addressed this issue.
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I doubt that prenatal environments play much of a role, but I am certainly open to other ideas. For the most part, I focus on the importance of postnatal environments.
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Dear Jinxer,
Aside from the degree of previous contact, even in the very rare cases where pairs are separated at birth and meet for the first time when studied, their similar behavior is still heavily influenced by the cultural/environmental cohort effects I mentioned.
The researchers’ 50% heritability calculation is meaningless for three main reasons: 1) The MISTRA researchers falsely assumed at all MZA behavioral resemblance was caused by genetics; 2) Heritability estimates do not show “how much” genes contribute to a trait, and should therefore be abandoned entirely in the social and behavioral sciences; 3) Most pairs were only partially reared apart.
Relating to your point about the data being “locked in a vault somewhere,” this seems to be the case. I discuss this in detail in my book, and briefly in my 12/15/2014 MIA blog.
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Thanks to both you and Steve for your supportive comments.
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To Jinxer and others. My MIA article on anecdotal reports of reared-apart twin pairs just came out:
http://www.madinamerica.com/2016/03/bewitching-science-revisited-tales-of-reunited-twins-and-the-genetics-of-behavior/
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Noel,
Steve’s comments captured what I was thinking and wanting to write. Outstanding analysis and outstanding writing. I greatly look forward to your future postings.
Best,
Jay
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Thank you Steve.
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Thanks for your reply. Since the topic was an examination of the alleged evidence that schizophrenia is caused by disordered genes, I mentioned the issues relating to birthrates, and the validity of the “schizophrenia” concept, only in passing. But of course, they are important issues in their own right, and have been covered very well by others. To clarify, I did not use the term “schizophrenic” or “schizophrenics” in the article. When these terms do appear, they are always found in quotations taken from other writers.
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Jinxer. Current genetic theories are based on genetic interpretations of the data, not on anecdotes, but the anecdotes weigh heavily in the public imagination. But they shouldn’t, since they prove no more about genetics than stories about the powers of astrology do about astrology, and so on. This is all in my book The Gene Illusion, and will be in a future MIA posting. My next posting will be about genetic studies of schizophrenia.
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Dear Jinxer,
These are very good questions. In my most recent book, “The Trouble with Twin Studies,” as well as my 2004 book “The Gene Illusion,” I explained why these stories about supposedly reared-apart twin pairs do not prove or even suggest anything about genetic influences on behavior. I am hoping to post something in my MIA blog on this topic by mid-January. Please look for it. Some of the points I raised in my earlier MIA blog on reared-apart twin studies relate to individual pairs as well.
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Dear Bruce,
Thank you for your important article, and for writing about about how mainstream psychiatry and psychology depoliticize and decontextualize human behavior, and seek to maintain the status quo. These are very important points.
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I agree with you, and I have pointed out in the past that genetically oriented researchers usually overlook countless real word examples running counter to their claims. Behavioral geneticists frequently refer to twin studies as “natural experiments,” but they overlook many other natural experiments that point to the importance of environment, such as the one you mention in relation to Australia and the crime rate.
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Thanks, William.
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Dear Steve,
Thanks. You make some really good points, and we must always keep in mind that the people/corporations/governments funding this research have an interest in diverting our attention from the environmental “controllable variables” you mention, in addition to many others.
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Thanks, Daniel.
Much appreciated.
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I really doubt it, but as always, the answer to the question of why people develop “mental disorders” lies outside the body, not inside.
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Hello. I have a MIA posting on reared-apart twin studies entitled “Studies of Reared-Apart (Separated) Twins: Facts and Fallacies.” Many of the main points are covered there, and my recent book “The Trouble with Twin Studies” covers these studies in depth.
For a number of reasons, individual stories of the supposed similarities of reunited reared-apart MZ pairs prove nothing about genetics. Dissimilar pairs, of which there are many, are not interesting news stories and do not support the typically pro-genetic orientation of twin researchers who conduct reared-apart twin studies.
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Dear Hermes,
Eugenic ideas and practices were widespread in Finland and other Scandinavian countries for much of the 20th century. A well researched academic book on the topic of Scandinavian eugenics is:
Broberg, G., & Roll-Hansen, N. (Eds.). (1996). Eugenics and the Welfare State: Sterilization policy in Denmark, Sweden, Norway, and Finland. East Lansing, MI: Michigan State University Press.
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Dear Fred,
Thanks. Black’s book is excellent. I would also highly recommend Allan Chase’s classic 1977 book on eugenics, “The Legacy of Malthus.” Simply a must read.
The word “eugenics” stopped being used openly in the 1960s and early 1970s. It was still used frequently in a positive sense until then, when journals such as “Eugenics Quarterly” became “Social Biology” only in 1968. Between 1944 and 1965, the American Journal of Psychiatry had an annual “Review of Psychiatric Progress,” with a “Heredity and Eugenics” section authored by Franz J. Kallmann.
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Thanks Steve
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Hello. Psychiatric researchers have been looking for faulty brains and faulty genes for decades, and have found none, as the APA officially admitted in 2013 (see below). They have found nothing, yet they continue searching while largely ignoring environmental causes because they mistakenly see psychiatric disorders as “highly heritable brain diseases.”
There are many environmental causes of dysfunction and distress other than “trauma.” The hand cleaning compulsion you mention is caused by people believing that they will contract a dangerous disease if they don’t wash their hands repeatedly. So it is necessary to help them question this belief, and to understand this belief in the context of their history and the social environment they grew up in and continue to experience. As Szasz pointed out many times, if a brain disease is discovered, the condition ceases to be a psychiatric disorder, and becomes a neurological disorder.
For the APA admission that they have found no genes or biomarkers, see http://www.psychiatry.org/advocacy–newsroom/newsroom/statement-from-dsm-chair-david-kupfer-md
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Paula,
It doesn’t appear that you read the entire article. Towards the end, I wrote:
“In their 2013 work Mad Science: Psychiatric Coercion, Diagnosis, and Drugs, Stuart Kirk, Tomy Gomory, and David Cohen showed that there are serious reliability and validity problems in psychiatry, suggesting that research is impaired when it relies on the DSM to diagnose people with similar problems. A lack of reliability and validity has important implications for psychiatric genetic family, twin, and adoption studies—and accompanying heritability estimates—because many people diagnosed in these studies may not actually ‘have’ the condition at all.”
In any case, the article was about the claims of people who do see these categories and valid, reliable, and “heritable.” This was not the place to go into an elaborate debunking of the of psychiatric disorder (“mental illness”) concept, which many other MIA authors have done very well, and for the most part I agree with them on this point and have said so in previous books and articles.
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Thanks Norman. To put it simply, to identify the causes of emotional suffering and behaviors that fall into DSM categories, we must look outside of the brain and body.
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To Steve and Elahe,
Thank you. Heritability is a difficult concept to grasp, which is a major reason why it is not challenged as often as it should be.
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This is true, yet heritability estimates are based on the assumption that genetic and environmental influences are additive.
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Dear Karen,
I agree that psychological characteristics are difficult to define, yet all claims about genetic influences on them assume that they are valid quantifiable concepts.
The conclusion that nature and nurture are “tied” is based on the claim that most behavioral traits are 50 heritable. In my next posting, I plan to look at the misleading “heritability” concept itself.
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Steve,
Thanks for your support.
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Thanks, Eric. I appreciate your comments.
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Hi. My first article on reared-apart twin studies appeared in 2001. It can be downloaded from the Publications page at my website. I also covered the topic in Chapter 4 of my 2004 book The Gene Illusion.
But by far the most in-depth analysis of the many problems and biases in reared-apart twin research is found in my new book, The Trouble with Twin Studies: A Reassessment of Twin Research in the Social and Behavioral Sciences. For more information on this book, including a link to chapter summaries, please see http://www.jayjoseph.net/the_trouble_with_twin_studies
I am thinking of posting on this topic in the near future.
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Thanks, Steve.
You make some interesting points about twins, and researchers do tend to overlook many obviously problematic aspects of twin research. I think you will like my upcoming book, where I cover many of the central concepts and methods of behavioral genetics from a critical perspective.
Jay
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Hi. Like all such claims since the 1960s, this one is unlikely to hold up. An additional point is that, in the unlikely case that the results are confirmed, this would seem to invalidate every study ever done that used the singular concept of “schizophrenia,” since what was previously viewed as one disorder was actually eight different disorders.
As far as C. Robert Cloninger is concerned, he has made subsequently non-replicated schizophrenia “gene discovery” claims in the past. For example, in 2002 he published an article in the leading scientific journal PNAS, where he claimed, on the basis of three then-recently published studies, “For the first time, specific genes have been discovered that influence susceptibility to schizophrenia.”
(see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC129675/ )
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Thanks, Tom
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Eric,
I am glad that you are interested in further dialogue, and the dialogue of course would be open to various opinions. But I don’t think it is necessary for anyone to “give a little” when it relates to what a person believes to be true. Much better, in my view, would for all sides to state their case and leave it to others to decide who is right. I am glad that you are criticizing heritability estimates, which as you know critics have been doing for many years.
Regarding possible gene findings, I have stated that, given the history, all gene finding claims for behavioral traits and psychiatric disorders should be considered false positive until proven otherwise. But for me, the issue is really much more about approach . Even if some genes are eventually found for behavior, IQ, or psychiatric disorders, which I doubt will happen (in part because they would have been found by now), genetic approaches would remain a distraction and would continue to divert attention from the need to improve the environmental conditions that play a huge role in all aspects of human behavior, abilities, and physical health.
The behavioral genetic approach, in addition to being based on faulty science in my view, diverts attention from and actually helps prevent environmental interventions to improve the human condition. It is true that BG researchers frequently mention that the environment is important, but the BG approach leads people to think mainly in terms of genetics. And twin studies are one of the main reasons they continue to think in this way. But yes, more public discussion would be great. Finding areas of agreement on some points is fine, as long as the agreement is genuine, as I am sure you would agree.
Jay
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Dear Dr. Turkheimer,
First, I would like to say that I am pleased that you responded and that this dialogue is occurring. I make a point in my writing to represent everything truthfully and accurately, so I appreciate that you called my attention to this. However, I reread your 2011 “Still Missing” article and I must stand by my original statement, based on what I read there. That being said, the main question in light of the failure to uncover genes for behavioral traits and disorders, more than 13 years after the sequencing of the human genome, is the question of the validity of twin research. You and I clearly have different opinions about twin studies and the validity of the MZ-DZ “equal environment assumption,” upon which all genetic interpretations of twin method data are based. You might agree with me that there should be a greater level of public discussion about the value of twin research, with all sides of the issue participating in this discussion. I would welcome a collaboration with you on bringing this issue to greater public awareness, if you are interested.
Sincerely,
Jay
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Thanks Daniel,and thanks to Duane and others who liked the post. I really appreciate you support.
Jay
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Thanks Ted for reminding everyone of the terrible consequences that can results from being falsely seen as carrying, as they called it in those days, the “hereditary taint” of schizophrenia.
Jay
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Olga,
I appreciate you comments. Thanks.
Jay
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Thanks Ted,
Glad to be of help.
Jay
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Dear Luis,
I discussed the equal environment assumption of the twin method in both of my books, and more in-depth in an article that came out this year in The Journal of Mind and Behavior (2013, Vol.34, pp. 1-40). I also have some publications on ADHD and genetics, including a 2009 chapter and a 2000 article. All of these can be downloaded from my website at http://www.jayjoseph.net/publications
Thanks for your interest.
Jay Joseph
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Hi, the method you mentioned to calculate twin concordance is still widely used. It is called the “probandwise” concordance rate method. The probandwise method of double counting does not create concordance where there is none, but it serves to inflate concordance rates calculated as a simple percentage, which is known as the “pairwise” rate.
Since you mentioned the German psychiatric geneticist Ernst Rüdin, you may be interested in an article about him that I co-wrote that has recently been published. The URL is http://www.ncbi.nlm.nih.gov/pubmed/23180223
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