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Conceptualizing Intelligence and Modern Applications

At the heart of behavioural genetics is the nature vs. nurture debate which, for years, has examined various human traits. However, there is little dispute concerning the trait of intelligence. Many experts agree that genetics and individual environments display a unique interplay that results in the expression of intelligence in persons. The two factors do not operate independently of one another; rather, each is amplified by the presence of the other (MacNeil, 2005). Recognizing the interaction of genetics and environment is key in ensuring the highest standard for quality of life. Empirical evidence suggests that children can actually fluctuate in IQ by several points due to the interaction of their genotype and the environments they have subsumed (MacNeil, 2005).

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As proven by intelligence studies, intelligence is a mix of genetic and environmental factors. Through educational practices, preexisting genetic dispositions and abilities can be encouraged [this is an environmental effect] and nurtured to cultivate a student’s learning potential.

With the onset of COVID-19, many students who are genetically predisposed to certain types of learning and intelligence-i.e kinesthetic, visual, etc. are at a severe disadvantage. In a normal school year, these students would excel in an environment that encouraged their brand of intelligence, but now these same students struggle to excel as their environment negatively impacts their expression of IQ.

IQ: What We Know Already

These IQ tests quantify the interaction of genetics and environment through a statistical method called heritability. Heritability is defined as the extent to which variation in a particular

characteristic within a group can be attributed to genetic factors (MacNeil, 2005). To understand just how genetics and environment affect each other, there will be several references to heritability.

The Minnesota Twins Study

The first study, the Minnesota Twins Study, involved monozygotic twins that were separated in infancy and raised apart (Bouchard et al., 1990). Each set of twins in the study was tested for various psychological traits, with a stress on IQ. >100 sets of monozygotic twins and triplets raised apart (MZA) from several countries around the world were asked to complete approximately 50 hours of medical and psychological assessment.

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Throughout assessment, several measures were taken to ensure validity in the results.

Two or more test instruments were utilized in each domain of psychological assessment. In the domain of intelligence, IQ was measured by three tests: the Wechsler Adult Intelligence scale (WAIS), a Raven/Mill-Hill composite, and the first component of two multiple abilities tests. Separate examiners administered the tests to eliminate any influence from other participants. This verification was ascertained by friends, relatives, their adoption network, social workers, other professionals that acted as intermediaries for the twins, as well as extensive biological testing.

The results of study showed a surprising consistency of MZA IQ correlations across all of the measurement tools and countries involved in the study. The differences in correlations could be quantified on a very narrow range (0.64 - 0.74). This led to the suggestion that assuming no environmental similarity, genetic factors alone contribute to approximately 70% of IQ heritability. Very few members of the target group in the study experienced abject poverty, abuse, or illiteracy in their lives and were all healthy. Therefore, environmental factors had little effect in this situation. Rather, it was clear that genetics played a key role in the expression of IQ.

The emphasis on genetic influence can be further explained by the fact that the MZA twins had no previous interactions with one another growing up. The main cause of most psychological variance involves learning through experience, and these experiences, to some extent, are chosen by an individual, and these choices can be guided by an individual’s genetic makeup. Essentially, the developmental experiences of MZA twins may have led to high correlations in IQ because MZA twins will actively, due to their genetic influences, seek out and create similar effective environments for themselves.

Although MZT twins (MZ twins raised together) showed on average to have higher IQ correlations when compared to MZA twins, the argument of a lack of common rearing was disproved by the decrease in IQ correlation as MZT twins got older (Bouchard & McGue, 1981). Therefore, the small differences between MZA and MZT twins in IQ correlation cannot be explained through a lack of interaction at a young age.

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The Transracial Adoption Study

Two concurrent experiments started in 1974 and 1975 respectively. The two adoption experiments were designed to test the influence of environmental factors on IQ and to prove the existence of an intellectual reaction range (Scarr & Weinberg, 1983). The Transracial Adoption Study (TAS) used 101 transracial families with a total of 176 adopted children and 143 biological children of the adoptive parents. Among the adoptees, 111 were adopted in the first year of life and 65 after 12 months of age. Children in the study ranged in age from 4-18 years old, and this age range called for different IQ tests to be administered. The average age for the adopted children was 7, and for biological children it was 10. Children from 4-7 years old received the Stanford-Binet test, children from 8-16 received the Wechsler Intelligence Test for Children (WISC) and older children and all parents received the WAIS.

The second experiment was the Adolescent Adoption Study(AAS), involving 194 adopted children in 115 adoptive families. The control group consisted of 237 biological children in 120 families. All of the adoptees were placed in their families in the first few months of life, the median being 2 months of age. From 1975-77, both groups of children were 16-22 years old. Both samples of parents were of similar socioeconomic status (working to upper middle class) and of similar IQ levels on the WAIS.

In the TAS experiment, both parents and biological children of the families scored on the “bright” average to higher end on age-appropriate IQ tests (Scarr & Weinberg, 1983). The black and interracial adopted children were also found to score above the average of the white population, regardless of when they had been adopted. Black children adopted in the first 12 months of life scored, on average, an IQ of 110, 20 points above comparable children being reared in the Black community. This significant jump can solely be explained by the change in environment and not racial differences in genetics. Adoptees were now immersed in intellectually stimulating homes where they were immersed in the culture of the IQ tests and schools. This enabled them to perform equally as well as non-Black adopted children outside of the study in similar families. Results also showed that the IQ heritabilities calculated for young siblings in the study were extremely high, even though there was no immediate genetic relatedness.

In the AAS experiment, adopted children's IQ scores were more closely correlated with the educational levels of their biological mothers and fathers (.28 and .43) than with their adoptive mothers and fathers (.09 and .11). Adopted children's IQ was highly correlated with their biological parent's education, as were those of the adolescents in the biological sample (Scarr & Weinberg, 1983). Results also showed that the heritabilities calculated for biologically related siblings was similar to that of unrelated siblings in the TAS, however that of adopted children reared together for 18 years was zero. Unlike the TAS study, which involved a much younger and diverse demographic, the adolescents (all identified as white) raised together from infancy did not resemble their genetically unrelated siblings. This can be explained as an environmental truth that is easily observable. Older adolescents are largely liberated from their family’s influences and are freer to select their own environments, which ultimately shape traits like personality and intelligence. It is clear from both the TAS and AAS studies that IQ is malleable and can change dramatically based on specific environments. This plays nicely into the idea of a reaction range. Adoptees in both studies were responsive to the rearing environments in adoptive families, which as a group provided intellectual stimulation and exposure to the skills and knowledge sampled on the IQ tests. The average IQ scores of both samples of adoptees are above the average of age mates, primarily because they benefit from their rearing environments.

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Implications for Modern Learning

IQ is indeed based on genetics and environment, but how is intelligence that is used specifically for learning in school systems affected by these factors? Having a certain educational environment can maximize genetic capabilities by developing cognitive functions [like studying, attention span, and reading comprehension of texts].

Giving students with certain learning capabilities the opportunities to use them (i.e for audio learners, giving them opportunities to exercise audio learning through videos, recordings, and lectures) can develop neural plasticity (the capability for a person’s synaptic connections within the brain to develop over time)

The opposite is also true-depriving children of environments that will maximize genetic potential can have disastrous effects on natural intelligence. For example, early childhood traumas and deplorable educative environments can increase glucocorticoid receptor regulation in the brain, which can over time manifest in demotivated and depressive behaviours.

For obvious reasons, this would be ineffective for developing successful learning in children. Specifically with the onset of the pandemic, children ae at greater risk for learning in “deplorable educative environments”.

Whether this be adverse home environments, or simply online learning not suiting a kinesthetic learner, many growing children are at risk for an early pruning of their genetic learning capabilities.

Possible Solutions

By definition, kinesthetic learners tend to be naturally active individuals and should have a hands-on approach to learning. Whenever possible, kinesthetic learners should be manipulating objects, conducting experiments, drawing, etc. Specifically for these learners, some coping strategies can include:

  • Incorporating movement into studying by taking frequent movement breaks

  • playing with a fidget spinner

  • sitting on a balance ball,

...all can help kinesthetic learners engage with and remember information.

Having teachers dedicate time , when possible, for students to interact with one another and build relationships that they normally would have engaged in offline during pre- and post class conversations and extracurriculars.

Online school does not suit all of our students and, as we've discussed, can put many at an inequitable disadvantage. With taking these into account, our approach to childhood intelligence and learning could improve greatly. Specifically regarding COVID-19, teachers and parents can begin to better adapt with these strategies in mind, in order to create the best learning environment possible for their children.


MacNeil, J. (2005). Psychology--frontiers and applications, second Canadian edition Passer,

Smith, Atkinson, Mitchell, Muir. McGraw-Hill Ryerson.

Bueno, D. (2019). Genetics and Learning: How the Genes Influence Educational Attainment.

Frontiers in Psychology,10. doi:10.3389/fpsyg.2019.01622

Practicing Effective Learning Strategies During COVID-19. (2020, September 22). Retrieved

from https://www.westislandtherapycentre.com/practicing-effective-learning-strategies-during-covid-19/

MacNeil, J. (2005). Psychology--frontiers and applications, second Canadian edition Passer,

Smith, Atkinson, Mitchell, Muir. McGraw-Hill Ryerson

Bouchard, T., Lykken, D., Mcgue, M., Segal, N., & Tellegen, A. (1990). Sources of human

psychological differences: The Minnesota Study of Twins Reared Apart. Science, 250(4978), 223-228.doi:10.1126/science.2218526

Scarr, S., & Weinberg, R. A. (1983). The Minnesota Adoption Studies: Genetic Differences and

Malleability. Child Development, 54(2), 260. doi:10.2307/1129689

Bueno, D. (2019). Genetics and Learning: How the Genes Influence Educational Attainment.

Frontiers in Psychology, 10. doi:10.3389/fpsyg.2019.01622

Practicing Effective Learning Strategies During COVID-19. (2020, September 22). Retrieved

from https://www.westislandtherapycentre.com/practicing-effective-learning-strategies-during-covid-19/

Article Author: Rahma Osman

Article Editors: Stephanie Sahadeo, Sherilyn Wen