Effects of Genetics and One's Environment on Intelligence

Ever wonder why some people just seem to be smarter than others? “Intelligence is the mental capacity to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn” (“Intelligence”). There are many theories of what intelligence is and how it should be defined, but three qualities: problem-solving ability, verbal ability, and social competence are all believed to be vital to one’s intelligence. Intelligence can be measured in many different ways. Most psychologists prefer to use “The Stanford - Binet test,” the first major intelligence test, which stresses testing in both verbal and mathematical skills. A large controversial issue among psychologists today is whether or not one’s intelligence is inherited, influenced by the environment one lives in, or a combination of both. This argument is also known as the “nature versus nurture theory” (Hetherington 428). Both genetics and the home environment are factors that help shape an individual’s personality, but do these two factors contribute to one’s level of intelligence? There is much evidence that supports both cases, and therefore each factor must be responsible for affecting an individual’s level of intelligence.

According to many studies, between 40% and 80% of the variation in human intelligence is attributable to genetic factors. “Genetic determination is the combination of genes that makes us what we are, or creates a characteristic” (Grasso). Inherited from our parents, genes are the codes for our personality, our traits, and our appearance. In saying this, intelligence is a trait and {Comma after and.} therefore, can be inherited in our genes. Psychologist Arthur Jensen argued and researched children of those marrying into the same social classes finding they would have the same range of intelligence as their parents. Twin studies, comparing identical and non-identical twins, were conducted by Dr. Paul Thompson from the University of California at Los Angeles, finding that identical twins had the same genes and showed approximately the same I.Q, and were much closer in relation then those that were not identical (Sternberg). Therefore, genetics ultimately has a role in a person's intelligence.

While it is still unknown whether genes determine the maximum intelligence ability of a person, genes are not the only thing that effect affect intelligence. Many environmental influences also can enhance, or deter diminish intelligence. Incidences both before birth and after birth can influence a child’s intelligence. For example, many congenital factors such as a mother’s use of drugs or alcohol and or oxygen deprivation can cause defects which would alter the child’s intelligence ability (Hetherington 430).

The family home environment also plays an influential role in the development of intelligence. Studies show that a supportive, warm, and loving home environment teaches a child to be independent and results in a more intelligent child than in an unsupportive home. Another factor that needs consideration is that the intelligence of a person increases with the amount of education that person receives. Positive attitudes toward learning influences the amount of schooling a person considers to go through. Living in cultures that support academic success and having friends that participate in activities like studying together increases a person’s interest in their education. One last type of environmental influence is that of the community’s. Children that live in isolated areas, such as rural areas, along with those that live in areas with unsafe housing and poor diet, can significantly hinder a child’s intellectual development, and these children will only develop a low level of intelligence (Hetherington 431).

Each environmental influence effecting intelligence can also have the reverse effect in some cases. For instance, one might realize that they are in a bad home environment, and do not receive the attention they need, and therefore focus on school and work to keep their mind off their home life. Another case could be people adapting to their environment and what is available to them and having the ability to create highly intelligent things with what they are given (Hetherington 432).

So, is our intelligence merely what we are given at birth and is determined by whether or not we are stimulated enough throughout our cognitive development to reach that maximum intelligence, or is our intelligence level predetermined by genetic factors only? Evidence shows that the many types of environments surrounding us and our genetic disposition affect a person’s intellectual ability. It is known that our current level of intelligence directly corresponds to either our genetics or our environment. However, in order to determine whether or not our maximum intelligence level is limited to either what we are given at birth or our environmental influences, more studies will have to be done.

Sources

Grasso, Fabian. "I.Q. - Genetics or Environment." AllPsych Journal (2002). 17 Mar. 2006 <http://allpsych.com/journal/iq.html>

Hetherington, E. Mavis, Ross D. Parke, Mary Gauvain, Virginia Otis Locke. Child Psychology. "How Much of Intelligence is Inherited?" New York: 2006. 428-432.

"Intelligence." Wikipedia. 17 Mar. 2006. <http://en.wikipedia.org/wiki/Intelligence_%28trait%29#Definitions_of_intelligence>

Sternberg, Robert J., Elena L. Grigorenko, and Kenneth K. Kidd. "Intelligence, Race, and Genetics." American Psychologist Jan. 2005. <http://www.apa.org/journals/releases/amp60146.pdf>