Tag: twins reared apart
Exploding the âSeparated-at-Birthâ Twin Study Myth
Supporters of the nature (genetic) side of the ânature versus nurtureâ debate often cite studies of âreared-apartâ or âseparatedâ MZ twin pairs (identical, monozygotic) in support of their positions. In this article I present evidence that, in fact, most studied pairs of this type do not qualify as reared-apart or separated twins.
“Three Identical Strangers” and the Nature-Nurture Debate
Three Identical Strangers is a riveting film describing the story of identical triplets separated at six months of age and reunited in early adulthood. Their story provides no evidence in support of the genetic side of the nature-nurture debate, but it does supply some evidence in favor of the environment.
What Do Twin Studies Prove About Genetic Influences on Psychiatric Disorders?...
Assessing the validity of psychiatric twin research is important because it relates to the question of whether the main causes of psychological distress and dysfunction are located inside of the human body and brain, as mainstream psychiatry claims, or outside of the body and brain, as many critics argue.
Bad-Science Warning: The âMinnesota Study of Twins Reared Apartâ (MISTRA)
The huge impact of the MISTRA, in addition to the harmful and regressive social and political policy implications that flow from it, necessitates a detailed analysis of the âscienceâ behind the studyâs major claims and conclusions. Here I offer a new critique of this famous and influential âseparated twin study.â
Schizophrenia Twin Research as Reported in The Gene: An Intimate History...
In his 2016 book The Gene: An Intimate History, cancer physician and researcher Siddhartha Mukherjee chronicled the initial idea of the gene, taking readers through the history of genetics up to the current âpost-genomeâ period by interweaving science, social history, and his own personal narrative. In the process he documented some of the crimes of the eugenics movement and the monstrous atrocities committed by German National Socialism in the name of eugenics and biology, while noting the Naziâs promotion of twin research. He also criticized aspects of intelligence testing and genetic theories of racial inferiority based on IQ tests. At the same time, Mukherjee supported and promoted many contemporary behavioral genetics positions.
Twin Method Assumptions are Indefensible, but are Useful to the Rich...
The wealthy, and the institutions they finance and promote, look favorably upon research whose authors claim that economic disparities are rooted in biology, and are not harmful to humanity as a whole. But there are countless obvious real-world examples showing that political policies, social struggles, and public health programs, including those involving the adjustment of income differences, lead to improved health and well-being.
Comments on Jeffrey Lieberman and Ogi Ogasâ Wall Street Journal Article...
The March 3rd, 2016 edition of the Wall Street Journal featured an article by past President of the American Psychiatric Association (APA) Jeffrey Lieberman and his colleague, computational neuroscientist Ogi Ogas. The article was entitled âGenetics and Mental IllnessâLetâs Not Get Carried Away.â In their piece, the authors started by expressing the belief that a recent study identified a gene that causes schizophrenia, and then discussed whether it is desirable or possible to remove allegedly pathological genes in the interest of creating a future âmentally perfect society.â The authors of the article, like many previous textbook authors, seem unfamiliar with the questionable âevidenceâ put forward by psychiatry as proof that its disorders are âhighly heritableâ In fact, DSM-5 Task Force Chair David Kupfer admitted that âweâre still waitingâ for the discovery of âbiological and genetic markersâ for psychiatric disorders.
“Mental Illness and Familial Influences”
"Let us be clear that claims about established genetic or biochemical causation for mental distress are, as things stand, entirely fictional," writes Dr Lucy...
“Bewitching Science” Revisited: Tales of Reunited Twins and the Genetics...
In this article I will attempt to debunk one of the great âscientificâ smoke and mirrors shows of the past half centuryâthe claim that stories of reunited separated MZ (monozygotic, identical) twin pairs indicate that heredity plays a major role in causing human behavioral differences. These stories, which are often used to sell the false ideology of genetic determinism, have entered the public imagination in a way that academic research results never could. Here I will show that these stories provide no evidence whatsoever that (as yet undiscovered) âgenes for behaviorâ influence human behavioral development.
Schizophrenia and Genetics: A Closer Look at the Evidence
âThe substantial hereditary component in schizophrenia,â a pair of researchers wrote in 1993, âis surely one of the two or three best-established facts in psychiatry.â But is it really? For mainstream psychiatry and psychiatric genetics, schizophrenia is âa severe mental disorder with a lifetime risk of about 1%, characterized by hallucinations, delusions and cognitive deficits, with heritability estimated at up to 80%,â or a âhighly heritable neuropsychiatric disorder of complex genetic etiology.â Many commentators have challenged these claims, and some have challenged the concept of schizophrenia itself.
Ernst RĂźdinâs Unpublished Family Study of âManic-Depressive Insanityâ and the Genetics...
Although it is axiomatic in psychiatry that genetic factors are involved in bipolar disorder (manic-depression), and that they play a predominant role, there currently exists little if any scientifically acceptable evidence that bipolar disorder and other âaffective disordersâ are caused by disordered genes. Given almost 50 years of gene discovery claims that were not confirmed by replication attempts, we must assume by default that current gene finding claims are false-positive results as well. In the 1920s, pioneering psychiatric geneticist Ernst RĂźdin decided against publishing his large family study of âmanic-depressive insanity,â most likely because the results did not fit his theories of Mendelian inheritance, and failed to support his advocacy of eugenic policies.
Twin Studies are Still in Trouble: A Response to Turkheimer
Human behavioral genetics and its allied field of psychiatric genetics are in trouble, as unfulfilled gene discovery expectations during the âeuphoria of the 1980sâ have continued to the present day, leading to researchersâ ânonreplication curseâ dysphoria of the 2010s. In my recent book The Trouble with Twin Studies: A Reassessment of Twin Research in the Social and Behavioral Sciences, I presented a detailed argument that genetic interpretations of the common âclassical twin methodâ finding that reared-together MZ twin pairs resemble each other more (correlate higher) for behavioral characteristics than do reared-together same-sex DZ twin pairs are invalid because, among other reasons, the twin methodâs crucial MZ-DZ âequal environment assumptionâ (EEA) is false.
A Debate on Twin Research Has Broken Out in American Criminology
The long-running debate on the validity of twin research recently resurfaced in American criminology, and has major implications for behavioral and medical twin research. Most twin researchers and their critics agree that reared-together monozygotic (MZ) twin pairs experience more similar environments than experienced by same-sex dizygotic (DZ) pairs, and we argue that the twin method is therefore unable to disentangle the potential influences of genes and environment on human behavioral differences, a conclusion supported by the failures of molecular genetic research.