Selectively breeding animals is the new direct way to study the genetic factors in personality. As per this approach, the scientist chooses the animals first, which strongly expresses the personality characteristics of interest and its breeds and after that, the selective breeding happens. It creates an heir, which has even stronger traits than the earlier breeds. The strength of these traits is assumed to exist in genetic origin. In this manner, scientists have studied worms, pigs, rats, and pigs. However, it is not useful for studying humans. For this psychologists have modified techniques offered by behavioral genetics. This is based on family studies, twin studies, and adoptive studies.
A family study: It is a procedure such as the selection of one person having the trait of interest â€” for instance, autism, is a developmental personality disorder. Examination of an individualâ€™s family tree from his parents, siblings, and children to other distant relations. Then scientists analyze the patterns of personality traits of his close and distant family members have and to what extent; however, it cannot study why.
Twin study: Here the researchers study the twinsâ€™ personality characteristics. Identical twins have the same set of genes, while fraternal twins have a shared set. Again, if the twins are raised together, then the twins will have an equal influence of genetic and environmental factors. After this, scientists compare the correlation between the traits of the personality of both twins. The result is divided into three parts- Heritability, Shared environment, and Non-shared environment. All three sources have simultaneous influence in a general twin study. The relative importance of each type is then determined.
An adoption study: It is a study of biologically related people, including twins. They can be both reared together or apart. Genetic influence on a trait is seen is more close to the biological parents than to adoptive parents. Environmental influence is more when the adoptee is more like adoptive parents. The results of all three studies are combined to get a final idea of the genetic influence and environment. It is also found that the influence of the shared environment (include parents and caretakers) is least on an adultâ€™s personality and more on a childâ€™s personality. Thus, it decreases with increasing age. Parents do provide children a nourishing and stimulating environment, but they cannot turn them into what they want to. It is out of the parentâ€™s control to control their children. In the case of the non-shared environment, it generally has the largest impact on personality. These factors include the â€˜leftoverâ€™ of genetic influence and immediate environmental influence. It makes us unique and different from others, add unique personality traits. Many times, unknown people have a greater influence on us, such as celebrities, influential people, politicians, historical personalities, colleagues, books, media, and others. They also have a lot of contributions in shaping our personality traits, especially when we are adults, more than parents.
Controversies related to Behavioral Genetics and Personality
Behavioral genetic research is also a controversial topic. The reason behind it is the inclusion of topics like intelligence, racial discrimination, violence, and sexuality. Inclusion of race and finding the origins of various races across the world is most controversial among them. In this, it is decided based on DNA samples collected from various classes of people. Then the DNA of two groups is studied to arrive at genetic and racial traits of people as a whole. It should also be understood that genetics does not determine all traits of personality. Brain structure, education, nutrition, upbringing, and inter-genetic interactions make this study extremely dynamic. Hence, any results of many studies, using however perfected methods, cannot study what the complexities of personality traits are. These non-shared environmental influences are largely random and indefinite. How which factor affects personality depends on how the contexts in human life change.