Creepy science: Nature (genes) are far more influential than nurture on cognitive ability

CONTEXT

For decades, researchers have been debating the relative importance of genetics and upbringing and environment on cognitive ability. Cognitive ability refers to the mental processes involved in acquiring, storing, and using knowledge. It encompasses a wide range of skills and functions that are essential for thinking, learning, and problem-solving. Cognitive ability is the mental competence that allows individuals to think, learn, reason, and solve problems effectively. It involves processes like perception, focusing attention, reliance on memory, language competence, and decision-making ability.

By contrast, intelligence is generally defined as the ability to learn from experience, adapt to new situations, understand and handle abstract concepts, and use knowledge to manipulate one's environment. It involves reasoning, problem-solving, and learning from experience. Cognitive ability is more about the specific mental processes involved in thinking, while intelligence is a broader concpet that integrates these processes for effective adaptation and problem-solving. Cognitive abilities are often assessed through tests targeting specific functions, whereas intelligence is measured through comprehensive tests aiming to capture a general cognitive capacity.

UPDATE

PsyPost writes about a recent research paper:

Genetics, not shared environments, drives 

parent-child similarities in cognitive ability

A new study published in Research in Social Stratification and Mobility suggests that the transmission of cognitive ability from parents to children is primarily driven by genetics, with little influence from shared environmental factors like family resources. The findings challenge traditional assumptions in social mobility research that often attribute these correlations primarily to socio-economic status.

The intergenerational transmission of cognitive abilities has long been a subject of interest because of its implications for social mobility and educational outcomes. Past research has shown that children often mirror their parents’ cognitive abilities, but it has been unclear whether this is due to shared genetics, shared environments, or a combination of both.  

The results provided evidence that the intergenerational transmission of cognitive ability is driven primarily by genetic inheritance rather than shared environmental factors. Across all age groups examined, the researchers found minimal evidence that parental cognitive ability significantly influenced children’s cognitive development through environmental mechanisms. Instead, the observed similarities in cognitive abilities between parents and children were largely attributed to shared genetic factors.  

The researchers also failed to find evidence for passive gene-environment correlations. These correlations occur when parents pass on genetic predispositions to their children while simultaneously creating environments that align with those predispositions—for instance, high-ability parents fostering intellectually enriching environments. Despite being theoretically expected, the study found no significant evidence for these correlations. This suggests that the family environment does not mediate the relationship between parental and offspring cognitive abilities.

Subjects were in 4 cohorts in the study

From what I can tell, the study included a reasonable sample size. The subjects in the study were both twins and their parents. The researchers used that to disentangle genetic from social influences on cognitive ability. The surprising result here is that cognitive ability is overwhelmingly due to parent's genes. Nurture factors such as upbringing, social class or other non-genetic influences had essentially no impact, even in children aged 5-6. This was highly unexpected because environmental factors were typically thought to have a stronger influence on cognitive ability in early childhood. 

The abstract of the research paper comments:

Using data from all four twin birth cohorts, covering an age range of 5–25 years, we further explore whether the contribution of both mechanisms varies over the life course. For all four cohorts, in any of the estimated models, social transmission [nurture] is very small and not significant. Genetic transmission [nature or genes], in turn, seems to be the primary mechanisms of intergenerational transmission of cognitive ability and becomes increasingly important with age.

This flies in the face of what I thought the situation was. If this research is replicated and it holds up as valid, it has at least one very troubling social and political ramification. Specifically, this data can be used to breathe fresh life to what I thought was debunked science theory called eugenics. 

Historically, eugenicists have attempted to alter the frequency of various human traits by promoting the reproduction of individuals considered genetically superior and inhibiting the fertility of those deemed inferior. The term was coined by Francis Galton in 1883, inspired by his cousin Charles Darwin's theory of natural selection, with the goal of enhancing desirable traits and reducing undesirable ones through selective breeding.

Eugenics had, and probably still has, a very nasty side to it. Eugenics was used to justify forced sterilization or segregation of those considered unfit. Eugenics belief gained popularity and power in the late 19th and early 20th centuries, influencing policies in many countries, including the United States. In the US, eugenics belief led to forced sterilizations and immigration restrictions. Although eugenics has been widely discredited due to (1) its association with scientific racism, (2) its misuse by the Nazis, and (3) assumptions believed to be flawed about genetics and human traits. At least with regard cognitive ability (and probably intelligence) his paper supports belief in eugenics.

Specifically, the data here clearly highlights the intergenerational transmission of cognitive ability. That could be interpreted by eugenicists as evidence that cognitive ability is a heritable trait that can be passed down through generations. They will argue that this transmission supports the idea of selective breeding to enhance cognitive ability in future generations. The findings here on the genetic basis of cognitive ability, the intergenerational transmission of traits, and the minimal environmental influence from parental cognitive ability could be used (or misused?) by those who believe in eugenics to argue for selective breeding practices aimed at improving cognitive ability in future generations.

This paper absolutely needs to be reproduced. Variants of it need to be designed and conducted. We need a lot more data and analysis to determine whether these results are real, a statistical fluke or the product of a flawed or unconsciously biased research protocol or data analysis. If the data are real, I think this knowledge could possibly spin out of control real fast in both society and politics.  

I checked the credibility of the journal this research was published in, Research in Social Stratification and Mobility, to see if it is a crackpot science journal. It is a reputable journal, in the top 25% of journals in its general research area.

By Germaine: Do I have an unreasonable hair trigger when it comes to feeling all kinds of threats? This one feels really creepy.