User:Ina301/Nature Nurture

Twins

Finally there are the Mallifert brothers in Chas Addams's patent office and their real-world counterparts: the identical twins separated at birth who both grew up to be captains of their volunteer fire departments, who both twirled their necklaces when answering questions, or who both told the researcher picking them up at the airport (separately) that a wheel bearing in his car needed to be replaced.

...

The second a twin study performed by the psychologist Nancy Segal she found a set of twins one raised in Nazi Germany as a Catholic, the other raised as a Jew in Trinidad. When they finally met in their forties they had identical blue shirts on, both wore rubber bands on their wrists, both loved to dunk their buttered toast in coffee, they flushed the toilet both before and after using it, and they both loved to sneeze in crowded elevators to watch everyone jump.

Sex

Remarks at NBER Conference on Diversifying the Science & Engineering Workforce - Lawrence H. Summers

Homosexuality

Studies

Header text	Header text	Header text
Kallman (1952)	36 MZ pairs and 26 DZ pairs	100% concordance rate for homosexuality among 37 monozygotic (MZ) twin pairs, compared to a 12%–42% concordance rate among 26 dizygotic (DZ) twin pairs
Bailey and Pillard (1991)	56 MZ twins, 54 DZ twins, 57 adoptive brothers, and 142 nontwin biological siblings	52% of monozygotic (MZ) brothers (of whom 59 were questioned) and 22% of the dizygotic (DZ) twins were concordant for homosexuality. 11% of adoptive brothers were homosexual and 9.2% of nontwin biological siblings
Bailey, Dunne and Martin (2000)	4,901 Australian twins	20% concordance in the male identical or MZ twins and 24% concordance for the female identical or MZ twins
Bearman and Brückner (2002)	289 pairs of identical twins and 495 pairs of fraternal twins	concordance rates for same-sex attraction of only 7.7% for male identical twins and 5.3% for females
Långström, Rahman, Carlström, Lichtenstein (2010)	more than 7,600 twins	Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance [of sexual orientation], the shared environment .00, and the individual-specific environment .61–.66 of the variance. Corresponding estimates among women were .18–.19 for genetic factors, .16–.17 for shared environmental, and .64–.66 for unique environmental factors. Although wide confidence intervals suggest cautious interpretation, the results are consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior

A meta-study by Hershberger (2001)[6] compares the results of eight different twin studies: among those, all but two showed MZ twins having much higher concordance of sexual orientation than DZ twins, suggesting a non-negligible genetic component.

Hjernevask (Brainwash)

Hjernevask - Part 1 - The Gender Equality Paradox: https://www.youtube.com/watch?v=cVaTc15plVs

Hjernevask - Part 2 - The Parental Effect: https://www.youtube.com/watch?v=41ryusHlrgw

Hjernevask - Part 3 - Gay / Straight: https://www.youtube.com/watch?v=b5iEnZt2t7k

Hjernevask - Part 4 - Violence: https://www.youtube.com/watch?v=P2pRbPydPjA

Hjernevask - Part 5 - Sex: https://www.youtube.com/watch?v=m951x1-nbNs

Hjernevask - Part 6 - Race: https://www.youtube.com/watch?v=Ve6uK00AvNo

[Hjernevask - Part 1 - The Gender Equality Paradox](https://www.youtube.com/watch?v=cVaTc15plVs)
[Hjernevask - Part 2 - The Parental Effect](https://www.youtube.com/watch?v=41ryusHlrgw)
[Hjernevask - Part 3 - Gay / Straight](https://www.youtube.com/watch?v=b5iEnZt2t7k)
[Hjernevask - Part 4 - Violence](https://www.youtube.com/watch?v=P2pRbPydPjA)
[Hjernevask - Part 5 - Sex](https://www.youtube.com/watch?v=m951x1-nbNs)
[Hjernevask - Part 6 - Race](https://www.youtube.com/watch?v=Ve6uK00AvNo)

IQ

Sibling similarity

The actual degree of personality and IQ similarity between biological siblings is quite modest, unless they are identical twins (Scarr & Grajek, 1982). The average personality correlation between full siblings is about .14 (Loehlin, 1992). The average IQ correlation between siblings is about .40. The IQ difference between ordinary siblings averages 12 IQ points, whereas randomly paired members of the population differ on average by 17 points (the standard deviation of IQ tests is 15; Jensen, 1980; Plomin & DeFries, 1980).

Nonetheless, degree of siblings' similarity in intelligence and personality follows genetic relatedness, not whether they were reared by the same parents (environmental relatedness). More generally, identical twins are very similar on all behavioral measures, much more similar than fraternal twins or siblings in the same family. Identical twins reared in different homes are nearly as similar in intelligence and personality as identical pairs reared in the same home, whereas adopted children reared in the same home hardly resemble each other at all (Loehlin, 1993; Plomin, 1994; Scarr & Weinberg, 1978; Scarr, 1992, 1993).

Resources

Intelligence: Born Smart, Born Equal, Born Different http://www.bbc.co.uk/podcasts/series/intelligence

Criminology

[Demonstrating the validity of twin research in criminology](https://www.researchgate.net/publication/267158254_Demonstrating_the_validity_of_twin_research_in_criminology)

[A Demonstration of the Generalizability of Twin-based Research on Antisocial Behavior](https://www.researchgate.net/publication/234011308_A_Demonstration_of_the_Generalizability_of_Twin-based_Research_on_Antisocial_Behavior)

[On the consequences of ignoring genetic influences in criminological research](https://www.researchgate.net/publication/266677671_On_the_consequences_of_ignoring_genetic_influences_in_criminological_research)

Heritability

Interesting discussions

How much should I trust heritability claims? - https://www.reddit.com/r/slatestarcodex/comments/4i9ap2/how_much_should_i_trust_heritability_claims/

Terms

Definition	Source	Ref
non-shared environment, a term that he coined to refer to the environmental reasons why children growing up in the same family are so different.	Source	ref
Shared environment is defined by Plomin as that which tends to make individuals similar	Source	ref
Shared environment effects are those shared by all members of a given family but that differ between families.	Intelligence: New Findings and Theoretical Developments	ref
The non-heritability proportion can be further divided into the "shared environment" which is the non-genetic factors which make siblings similar while the "non-shared environment" is the non-genetic factors which makes siblings different from another.	Source

Term	Example	Example
rGE	Example	Example
GxE	Example	Example
A, or a^2	additive genetic variance	Example
D, or d^2	non-additive genetic variance	Example
C, or c^2	shared environment	Example
E, or e^2	remaining variance	Example

Claims & Responses

1.

Dr. Feldman said heritability estimates also depended on technical details involving the statistical model. In the late 1970's, he said, investigators discovered that if they added I.Q. data on relatives of twins to the data on twins when estimating how much of I.Q. test results were due to genes, their heritability estimates were cut in half. Dr. Feldman contends that if Dr. Bouchard had used twins' relatives in his study, he would have had to change his estimate.

The ‘shock of the new’ referred to a reflexive, premature and generally negative response provoked by the emergence of modern art [1]. Inevitably, with time, distance and perspective a more balanced consensus evolved as it does for other ‘new’ things. The early genomic data for schizophrenia provide a fascinating parallel where many responses have been prematurely negative [2] or focussed on what genome-wide association studies (GWAS) didn’t find (the ‘missing heritability debate’) [3] rather than on the many novel, interesting findings that are emerging.

Questions

• If peers have an effect, could parents have an indirect effect by choosing peer groups?

1.

So has Harris solved the mystery of the Third Law, the unique environment that comes neither from the genes nor from the family? Not exactly. I am convinced that children are socialized — that they acquire the values and skills of the culture — in their peer groups, not their families. But I am not convinced, at least not yet, that peer groups explain how children develop their personalities: why they turn out shy or bold, anxious or confident, open-minded or old-school. Socialization and the development of personality are not the same thing, and peers may explain the first without necessarily explaining the second.

One way that peers could explain personality is that children in the same family may join different peer groups — the jocks, the brains, the preppies, the punks, the Goths — and assimilate their values. But then how do children get sorted into peer groups? If it is by their inborn traits — smart kids join the brains, aggressive kids join the punks, and so on — then effects of the peer group would show up as indirect effects of the genes, not as effects of the unique environment. If it is their parents’ choice of neighborhoods, it would turn up as effects of the shared environment, because siblings growing up together share a neighborhood as well as a set of parents. In some cases, as with delinquency and smoking, the missing variance might be explained as an interaction between genes and peers: violence-prone adolescents become violent only in dangerous neighborhoods, addiction-prone children become smokers only in the company of peers who think smoking is cool. But those {396} interactions are unlikely to explain most of the differences among children. Let's return to our touchstone: identical twins growing up together. They share their genes, they share their family environments, and they share their peer groups, at least on average. But the correlations between them are only around 50 percent. Ergo, neither genes nor families nor peer groups can explain what makes them different.

- The Blank Slate, p.201

Criticism of BG

http://www.tandfonline.com/doi/abs/10.1080/02680939.2016.1139189

Genetic Influence on Human Psychological Traits: A Survey

https://i.imgur.com/65ntAbS.png

Bouchard, Thomas J. "Genetic Influence on Human Psychological Traits: A Survey." Current Directions in Psychological Science 13.4 (2004): 148-151.

Meta-analysis of the heritability of human traits based on fifty years of twin studies

Polderman, Tinca JC, et al. "Meta-analysis of the heritability of human traits based on fifty years of twin studies." Nature genetics 47.7 (2015): 702-709.

Heritability in Criminology back and forth (2014-2015)

Back and forth between J. C. Barnes, John Paul Wright, Brian B. Boutwell, Joseph A. Schwartz, Eric J. Connolly, Joseph L. Nedelec, Kevin M. Beaver and Callie H. Burt and Ronald L. Simons

Header text
Burt, C. H., & Simons, R. L. (2014). Pulling back the curtain on heritability studies: Biosocial criminology in the postgenomic era. Criminology, 52(2), 223-262.
Barnes, J. C., et al. "Demonstrating the validity of twin research in criminology." Criminology 52.4 (2014): 588-626.
Burt, C. H., & Simons, R. L. (2015). Heritability studies in the postgenomic era: The fatal flaw is conceptual. Criminology, 53(1), 103-112.
Wright, J. P., Barnes, J. C., Boutwell, B. B., Schwartz, J. A., Connolly, E. J., Nedelec, J. L., & Beaver, K. M. (2015). Mathematical proof is not minutiae and irreducible complexity is not a theory: a final response to Burt and Simons and a call to criminologists. Criminology, 53(1), 113-120.

The Three Laws of Behavior Genetics and What They Mean

First Law. All human behavioral traits are heritable.

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

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

Turkheimer, Eric. "Three laws of behavior genetics and what they mean." Current Directions in Psychological Science 9.5 (2000): 160-164.

The Three Laws of Behavior Genetics and What They Mean

First Law. All human behavioral traits are heritable.

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

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

Turkheimer, Eric. "Three laws of behavior genetics and what they mean." Current Directions in Psychological Science 9.5 (2000): 160-164.

The Fourth Law of Behavior Genetics

On the basis of molecular studies that have measured DNA variation directly, we propose a Fourth Law of Behavior Genetics: “A typical human behavioral trait is associated with very many genetic variants, each of which accounts for a very small percentage of the behavioral variability.”

Pinker's Description

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.

Summary

Top 10 Replicated Findings From Behavioral Genetics Weak Genetic Explanation 20 Years Later. Reply to Plomin et al. (2016)