Scientists and academics have spent a lot of time and money over the years studying the trait of human intelligence, with the primary goal of identifying the causes that affect a person’s intelligence. The Intelligence Quotient (IQ) is a common indicator of this trait that is obtained from the composite total of many sets of tests that determine the efficacy of the human intellect (Meisenberg, 2003). The tests usually consist of easy to basic arithmetic, speed, and memory tests. In certain companies, such tests are used to screen career candidates. This form of testing helps in selecting the best candidates for job placements. IQ tests are also used for education placements as well as the process of assessing intellectual disability among individuals (Jensen, 1972). People with IQ scores of 140 and above are regarded as geniuses while those falling below the score of 70 are regarded as dumb. The average score for most people lies between 90 and 120 (David, 2010). Scientific observations have proved that there is a significant relationship in intelligence levels between people that with blood relations e.g. siblings and cousins. It thus becomes an important subject of interest, with experts gaining interest in determining the extent to which intelligence can be attributed to genetics. Genes can be transmitted from parents to their children and across generations. Genetic composition could thus be responsible for observable similarities, with IQ levels being significantly evident (Matthews and 2014).
In their research, experts have in the past used randomly selected sets of relatives and studied the observable elements regarding their intelligence. During the research, they study the differences and similarities between these individuals and the results have only proved the relationship between intelligence and genetic composition. It has been proven that adults with high IQ levels are likely to bear children with relatively high levels of intelligence. The converse is also true. Studies carried out on sets of twins show highly matching IQ scores in identical twins as opposed to the scores among fraternal twins. Studies also proved that similarities in IQ measures are higher in siblings than between cousins.
Studies have discovered that intelligence is determined by genetics and other external factors (Stanovich and West, 2014). These factors include the home environment where an individual is brought up, the kind of parenting especially during the formative years and the kind of education that one gets. Nutrition is also a key factor. During the early years in a child’s development, these external factors are quite significant and the influence of genetics on intelligence ranges between 40 to 50 percent. However, the correlation of IQ and genetics becomes higher in teenagers and adults when the individual has already been accustomed to their environment. Genes are responsible for IQ levels in adults to the tune of 75 percent (Plomin and Spinath, 2004). A key point to highlight is that genetics have a high correlation to an individual’s learning and cognitive abilities, reaching a high of 60 percent and above in learners. Genetics play a greater role in an individual’s learning abilities compared to other phenotypic factors. The underlying fact in this case is that young children are still discovering more about themselves and their surrounding, thus their intelligence could be affected by such environmental factors. On the hand, from teenage to adulthood, an individual is likely to have already got used to their surroundings (Money and Lewis, 1996). Therefore, factors such as genetics play a more significant role in their intelligence at this stage of their development.
Genes associated with IQ
In their course of their research, scientists have tried to identify the specific genes that can directly be linked with the trait of intelligence. It has been a difficult task as some of these genes have also been found responsible for causing various diseases in human beings. A good example is the APOE gene which despite being linked with intelligence, the gene is also responsible for conditions such as Alzheimer’s. The Single Nucleotide Polymorphisms genes (SNPs) have also been linked to human intelligence. Other potential genes are Cathepsin D (CTSD) which is also linked to schizophrenia. However, in the recent times, researchers have discovered genes appearing in clusters, which can be liked directly to human IQ. These are commonly referred to as the M1 and the M3 genes (Zimmer, 2008). The gene clusters have been proven to influence brain functionalities including memory, speed of information processing, attention and reasoning capacity. It is believed that these genes operate in clusters of many other genes and together to determine intelligence levels. Current research on these networks indicates that the genes could be operated by centralized master switches (van der Maas et al., 2014). Efforts are currently underway to study these master switches and the final breakthrough is expected in a few years time.
In conclusion, it is indeed true that genetics play a big role in determining human intelligence. High IQ is associated with factors such as great learning and cognitive skills, high-speed memory and fast information processing. Research has identified specific genes such as the M1 and the M3 genes that are directly linked to intelligence levels and further studies are currently in progress. There is no doubt that children can inherit intelligence from their siblings. Genes are responsible for IQ to a larger extent in teenagers and adults than in children (Werling and Sanders, 2016). The reason is that children are still in the process of getting accustomed to their environment.
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