Genetics has a significant influence on behavior, especially intelligence. Genetics is the way traits are passed from parent to offspring through heredity. It is evident that intelligent parents tend to have children of a higher intelligence. However, it is not evident without investigation how much intelligence is due to genetics and how much is due to the raising environment.
Clearly, a supportive environment can help a child with achievement in school, but the environment isn’t the main influencing factor. Consider an adoption situation. If a child is adopted into a home where there isn’t a huge emphasis on education, they may still do well in school due to intelligent birth parents. Conversely, if a child of lower intelligence is adopted into a home where education is central to the family, they can only do as well as their natural intelligence will permit. This indicates that the environment does have some influence on intelligence, but perhaps not as much as genetics. One way to factor out innate differences in intelligence is to study identical twins through twin studies. Twins are genetically identical, so their genetic intelligence should be the same. Thus, studies like the Minnesota Twin Study provide deeper insight into the effects of the environment on intelligence.
From 1979 to 1996, Dr. Thomas Bouchard did a longitudinal study on the effects of the environment on intelligence. Bouchard used pairs of monozygotic (identical) twins because he thought that their genetic intelligence should be the same. He studied sets of monozygotic twins reared apart and monozygotic twins raised together. His theory was that genetics played more of a role in intelligence than the environment, so twins reared apart and twins reared tog...
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...l or psychiatric history. While volunteer participants tend to be a little more highly motivated than randomly selected participants, this motivation shouldn’t cast so much of a difference on the results that they don’t apply to other people in a way similar to results from random participants. And while environments aren’t identical for twin reared together, the environments of each aren’t so drastically different that it will impact the results too greatly.
In conclusion, genetics have a very significant role in behavior. In relation to intelligence, research finds that genetics accounts for about 70% of human intelligence. It also accounts for many, many other personality traits. However, until we have a complete understanding of each gene in the human genome, further testing will be valuable in gaining deeper insight into the exact role of genetics on behavior.