Influences on Intelligence

We all know someone who has a very high IQ - maybe a friend who can solve math problems quickly or someone who appeared to be a "walking encyclopedia". Maybe you've asked yourself, how did he get so good at this? Did he inherit his high intelligence from his parents? Did his environment shape his intelligence?Two questions need answers: Is there a gene for intelligence? And, is intelligence genetic or environmental?

• We will dive into genetic influences on intelligence first.
• Then, we will explain what the biological influences are on intelligence.
• We'll look at how heredity influences intelligence.
• Lastly, we will look at environmental factors that impact intelligence.

Genetic Influences on Intelligence

There is no one specific gene that will dictate a person's level of intelligence. Instead, it is a combination of different genes influencing different components of intelligence. The CHRM2 gene has been identified to stimulate brain connections involved in various cognitive activities and associations of the SNAP-25 gene in nerve cell communication. Specific sequences in the dysbindin-1 (DTNBP1) gene can produce minor differences in IQ.

In a meta-analysis including data from over 78,000 individuals, researchers found 40 genes, of which the FOXO3 gene and CSE1L gene had the strongest association with intelligence, with a role in apoptosis, or cell death (Sniekers et. al, 2017; as cited in Carson, 2017). This suggests that intelligence may also depend upon the preservation and normal functioning of the nervous system.

Is Intelligence Genetic or Environmental?

The answer is that both genetic and environmental influences can affect intelligence. As shown in twin and adoption studies, genes have a more significant impact on cognitive differences than environmental influences. IQ similarities are stronger among identical twins than in those less genetically related, such as adopted children and their adoptive parents.

Fg. 1 Do genetics impact intelligence? pexels.com

The evidence of environmental factors shows that children are not born with fixed levels of intelligence.

On the other hand, other psychologists feel that a child's formative environment shapes intelligence, such that exposure to different settings can affect the development of cognitive skills.

Biological Influences on Intelligence

Let's look at some biological factors that are non-genetic in nature.

The thickness of the outer layer in some brain regions (e.g., frontal and temporal lobes), and the volume and number of nerve cells have been linked to intelligence. The temporal lobes mainly focus on memory, verbal, and non-verbal learning, while frontal lobes are responsible for the mental skills needed in daily living, such as planning, organizing, and even behavioral and emotional responses in achieving one's goals.

Hereditary Influences on Intelligence

Twin studies demonstrate a genetic aspect in people's IQs. Identical twins show similarities in brain structure and function and intelligence in other areas such as music, sports, and language. Even their IQ test results are comparable to those who took the same test twice.

Among adopted children, similarities in intelligence with their adoptive families are apparent in childhood. As they grow older, these similarities wane as experiences accumulate, and they become more like their biological parents, exhibiting genetic influences on intelligence. The impact of genes on intelligence becomes stronger in adulthood.

Fg. 2 Culture can influence intelligence, pexels.com

Cultural Influences on Intelligence

Language, customs, and early-life experiences affect the intelligence scores of children whose culture doesn't emphasize Western schooling, or those who aren't well-adapted to the types of questions seen in conventional intelligence tests. Certain cultures prepare children to adapt to the environment in which they live, where they are expected to farm or have certain occupations that don't need formal schooling.

Families' conversational styles can also affect how well a child does in intelligence tests.

Influence of Environment on Intelligence

Let's now look at how environment impacts intelligence.

Family Environmental Influences

As you may expect, the familial environment is seen as having a big impact on intelligence.

Parents' Educational Background and Culture

Parenting practices shaped by culture also affect IQ and test scores, such as in one experiment conducted by Segal and Hur (2008; as cited in "IQ: Greatly Influenced by Early Family Life," 2015).

Home Environment

Chaotic family environments (e.g., loud noises) and adverse events experienced in early life negatively affect children's intelligence. They have lower scores on IQ tests and struggle in cognitive development. Insufficient intellectual and emotional support also affects intelligence. Ensuring a positive home environment may help increase children's intelligence.

Socio-economic Status

Children with parents who have higher incomes tend to have higher IQs than those from low-income families. Poverty also lowers IQ; averages in IQ of children from lower socioeconomic groups are lower than middle-class children by about 10-15 points (Bearce, 2009). Problems with access to healthcare also add to the burden.

Parent-child Relationships

Intelligence increases when a child feels cared for, encouraged and loved in his early years. Family nurture displays a more significant impact on intelligence in children's early years; those with higher IQs experience more positive environmental influences. Here we can see the importance of parent-child relationships as parents are the child's first teachers; it is essential to create experiences that will positively impact their intelligence.

Education

A link exists between the length of schooling and children's intelligence. Baltes and Reinert (1969; as cited in Deary and Johnson, 2010) found that 8-year-old German children who got an extra year of schooling performed similarly to 10-year-old students who had the least amount of schooling. Overall, school attendance promotes intelligence because of cognitive abilities learned there, such as metacognition. Intelligence also declines among school dropouts for every school year missed.

Nutrition and Physical Activity

Nutrition also affects IQ, in that children who receive adequate nourishment have higher IQs than children who experience malnutrition. In addition, a pregnant mother's consumption of toxic substances can result in issues like fetal alcohol syndrome, which causes mental decline, language delays, and poor motor coordination. Children who engage in physical activities tend to have higher IQs, as seen in a study where the high IQ group did more than five hours of exercise per week (Makharia et al., 2016).

Place of Residence

Makharia et al. (2016) researched 1,065 Indian children between 12 to 16 years, finding that those who lived in cities and towns had higher IQs than those in the villages.

Importance of Environmental Influences on Intelligence

Environmental influences allow for opportunities to promote intellectual stimulation that will, in turn, help shape children to become healthy and productive adults in the future. What nature lacks, nurture can help fill in the gaps. Environmental influences strengthen or weaken intellectual growth.

Identification of environmental influences helps emphasize the positive early life and educational experiences and provides programs and interventions, especially for disadvantaged children from low-income families or with developmental delays.