To what extent does genetic inheritance influence behavior

To what extent does genetic inheritance influence behavior?

For years and years, there has been endless debating on whether human behavior is predetermined by genetic inheritance. The question that behavior was due to the transmission of genetic material from parents to offspring or construction by the surrounding environment had one of humanity’s greatest mysteries (medpdia). However psychologists and scientists have finally concluded that human beings are a product of combination of nature and nurture. No longer does any researcher with any reputation claim one over the other, it has now become a question of how much. Genetics definitely do influence our behavior, but to what extent? Trying to solve this question, psychologists and scientists look towards research on twins for clues. The main feature of these studies is that identical twins share the same genetic inheritance. Therefore, this allows psychologists and scientists to analyze the difference in twins’ behavior and conclude which of two: genetic inheritance or environmental factor, have influenced their behavior the most. Supported by the studies of identical twins’ similar IQ scores and sexual preferences, genetic inheritance influences behavior to large extent.

The study of twins in the psychological world today elucidate the best clues into how genetics influence behavior. Researchers enthusiastically seek out twins that have been separated from birth to study their similarities and differences. Thomas Bouchard from the University of Minnesota has conducted studies on over 8000 pairs of twins some identical and some not. According to Thomas Bouchard’s twin studies, which tested the twins’ Intelligence Quotient (IQ), intelligence is “69-78% heritable”, concluding that since IQ is heritable more than 50%; therefore, genetic inheritance influences human intelligence as well as their behavior to large extent. Intelligence is an integral component of how our brain operates, and the fact that it can be heritable raises serious questions about how we can develop it. Moreover, a case study on the twins Ms. Herbert and Daphne by Bouchard illustrated that although they were separated in early stage of their life, they showed remarkably similar personalities and mannerisms (Bouchard, IQ studies). Even though Ms. Herbert and Daphne were both brought up in different environments under different step-parents, the fact that they possess similar characteristics to each other concludes that genetic inheritance to large extent determines human behavior. Therefore, the twin studies and the case study on Ms. Herbert and Daphne supports the conclusion that although environmental factors do effect human behavior as well, genetic heredity plays a massive role in our development in personality or characteristics.

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Intelligence however, is just the beginning to understanding how truly heritable traits of our minds are. Studying human sexual orientation is an integral part of our understanding of genetic influence. If we truly are products of our genes or environment, how much of what designates our sexuality in the future? According to the case study on Australian identical twins, homosexuality was 20% heritable in men and 24% in women. Moreover, National Cancer Institute researcher reported that “many homosexual men appear to inherit a gene from their mothers that influences sexual orientation”. Adding to this report, Dean Hamer, the chief of the cancer institutes's Section on Gene Structure and Regulation, claimed that “people have no control over the genes they inherit and there is no way to change them” implying that homosexuality is not a choice or a simple decision but determined by the genetic inheritance. Studies on the family histories of 114 gay men showed that there were more homosexual brothers, uncles and male cousins than the general – heterosexual – population. Like the twin studies, mentioned in previous paragraph, these studies on homosexuality in a family contain the feature that these relatives or members of a family share common genetic inheritance but were raised in different environment. Although these members of a family were brought up from different environment and have different personal experience, they share the common genetic inheritance which, in this case, is homosexuality. To the question of where homosexuality mainly comes from, it can be answered that members of a family and twins as well as relatives, tend to have similar characteristics including sexual preference. Therefore, supported by the studies of homosexuality further supports the concept of heredity affecting our behavior.

However, it is important to note the other side of the spectrum as well in this long-standing argument. The value of environment and development through age is just as critical as their heredity. Although studies of twins’ IQ support the argument: to large extent genetic inheritance influence, similar outcome is resulted from studies of adopted children who have no blood relations with their step-parents, meaning that they have different genetic inheritance. Although the adopted child does not share any common genetic inheritance, his IQ scores are related to the step-parents. Moreover, it is critical to note that although genes do affect behavior, it may not be expressed due to the environment. If genes do cause homosexuality, than in a society where homosexuality is taboo, it would not be shown and therefore never accounted for. In addition to IQ or sexuality, other aspects such as religion, interests and hobbies are only some of which that differ from person to person no matter their genes. Thus, while to large extent genetic inheritance influence human behavior, we should keep in mind that environment is also a critical factor. To even understand the impact of heritability, environment is a critical part that needs to be analyzed. Even traits that are highly heritable are open to changes. Experience can modify anything in our lives. Although you may be naturally impulsive or rash, years of learning how to control yourself and calm parenting may cause you to be calm and collected. It is also critical to note that although genes do affect behavior, it may not be expressed due to the environment. If genes do cause homosexuality, than in a society where homosexuality is not accepted, people would suppress and hide it. Although genes play a large role in determining our behavior, it is without a doubt that environment does as well.

Overall, while human beings are product of both genetic inheritance and environmental factor, to large extent genetic inheritance influences behavior more than environmental factor does. Supported by the twins’ IQ studies and homosexuality studies, it is concluded that despite the research participants, separated identical twins were raised from different environment, showed similar behavior since they share the common genetic inheritance. One of the most critical questions of our time, discerning the human mind’s behaviors is only the gateway to unlock new potentials in humans or curing psychological illnesses. It will still take years of learning for us to truly decode how much of one’s brain in influenced by nurture or nature.