IB Psychology - To what extent does genetic inheritance influence our behaviour?

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Essay Question: To what extent does genetic inheritance influence our behaviour?

        A common saying goes, “You have your mother’s genes, so you should be good at this!” This statement demonstrates that common belief dictates that our genes that we inherit influence our behaviour. Yet, how true is this statement? Genes are heredity processes that we receive from our parents that are a factor that determine our characteristics and behaviour.

In layman’s terms, they are the building blocks that define our coarse, rough behaviour, but fail to closely define our closer instincts and actions. That is where the environment comes in to play a role. Thesis: While genetics certainly do play and define a role in complex behaviours such as intelligence and aggression, they only do up to a limited extent; environment is the defining factor in such acts of behaviour. 2-3 Sentence Explanation: Twin studies and adoption studies point out that ultimately the environment is a defining factor within intelligence and learning potential, measured by IQ tests. Evidence from studies conducted on aggression suggest that the environment is a deciding factor in anti-social behaviour.

        

        Twins have always been a fascinating example of how the environment affects the character and behaviour of the respective children in terms of their differing intelligence. We see in many instances that researchers use genetically identical twins (who were separated shortly after birth) as a window to glimpse their development with a different “nurture” from their twin counterpart. The reason that such projects are being done is because that the twins’ genetic makeup is identical, guaranteeing less margins of error.  One prime example of such a study is the Minnesota Twin Study in 1990 that compared identical twins that were raised apart from each other due to certain situations, like adoptions and foster care. The findings of the study were that roughly seventy percent of intelligence (measured with the Intelligence Quotient Exam) was attributed to genetic inheritance, while the remaining thirty percent was attributed to other extraneous factors. The study’s limitation is that it used a narrow measurement (in this case, the IQ test) to measure their intelligence, and the method used to allocate their intelligence to genes or other factors was not a “tested” and solid method of approach. Yet, this study demonstrates to us that indeed, while the twins were exact in genetic makeup, their differing environment led them to differ in intelligence. This study is significant because it offers insight that indeed, our environment plays indeed a capacity in determining our behaviour, even if it is the alleged “30%” of an extent.

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        Another method of finding out the correlation of genetics compared with intelligence is taking a look at adoption studies. This is significant because the child who is adopted will not have any genetic makeup that is identical to which of his or her guardians, hence partly eliminating the genetic factor while demonstrating the effect nurture plays on the subject (adopted child). Prime studies of this are the Minnesota Trans-Racial Adoption Study conducted by Scarr and Weinburg, which measured IQ testing scores of roughly a hundred children of minority ethnic groups who were raised under white families who were well ...

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