Psychology is essential in our lives as it helps us explain how and why we act the way we do. Therefore, a professional psychologist can assist individuals in improving their behaviour, management of stress, and decision-making by understanding their past behaviour and projecting a better future for them. One of the main sectors in psychology is behavioral genetics. Behavioral genetics studies the effect of a genetics’ lived experiences and makeup within a unique environment on their recent behavior. Geneticists aim to understand how differences in people have developed in recent times through the interaction of the environment and genes. Behavioral genetics’ main aim is to determine the relationship between environmental changes and genetic traits affecting particular behaviors and identify the strengths and weaknesses associated with the relationship. The studies assert that the present behaviour of human beings is created by exposure to their surroundings and genes. This paper will define behavioral genetics, describe adoption and twin studies associated with the study, and include several cautions related to hereditary studies.
Adoption studies in behavioral genetics compare the rates in which a behavioral trait is shared among adopted relatives and relative related biologically. On the other hand, twin studies compare those rates shared between fraternal and identical twins (Tikhodeyev & Shcherbakova, 2019). However, both studies offer important information about the relative essence of environment and genes influencing someone’s behavior. Many studies claim that there is a strong relationship between nature and nurture. Therefore, it is hard for scientists to determine the cause of a particular behaviour as nurture or nature (Friedman et al., 2021). Adoption and twin studies offer scientists an effective foundation for studying the essence of any possible risk factors on a condition or behavioural trait by regulating the variation of genetics.
Mainly, twin and adoption studies are focused on the twins’ behavior found in the same family surroundings and identify if the behavior is more influenced by environmental changes or genetics. Although there are multiple variations in twin studies, scientists tend to measure if the twins are fraternal or identical. Identical twins share all their genes, while each twin in a fraternal relationship is shared equally (Jansen et al., 2015). Therefore, scientists use this information to analyze whether environmental variables or the genetic makeup influences the twins’ behavior. Studies claim a huge and effective advantage in adoption and twin studies in understanding factors that lead to specific behaviour traits. For instance, fraternal twins’ body height and spoken language are the same, and they are normally the same height, unlike other family members. This example explains how genetics perform a huge role in shaping behavior and determining the height of people.
It is important to note that adoption and twin studies are used in a broader concept of understanding and analyzing behavioral genetics using the nature versus nurture debate. Quantitative genetics are also used to understand the role of genetics and environment in influencing behavior. The study involves analyzing similarities in people using their biological relationships (Plomin et al., 2013). For instance, they can use twins, cousins, half-siblings, and siblings raised separately or separated from each other at birth. According to multiple studies, both adoption and twin studies have provided us with complete and reliable evidence about the origin of behavioral traits. It is clear that some traits come from genetics while others are inherited. However, as we dive in to these studies, everything seems to support genetics as the main cause of behavioral studies. Genetically related individuals have the same traits and physical appearances in terms of mental illness, personality, intelligence, weight, and height (Charney, 2012). There tends to be some genetic bias from several behavioral traits. For instance, adopted studies claim that adopted children look alike to their biological parents regardless of their being separated for a long time.
Despite the studies being useful in identifying the effect of environmental variations and genetic makeups on behavioral traits, there are several cautions and assumptions surrounding twin and adoption studies. The main caution and limitation associated with these studies is the missing heritability whereby behavioral genetics estimates are unexpectedly higher than the difference provided by usual genetics and environmental changes (Rimfeld et al., 2019). Other cautions include stratification of population, assortative and epistasis parenting leading to multiple types of twins. Random mating assumes that individuals mostly seem to choose their partners with different traits rather than those with the same behavioral traits. This explains why fraternal twins would have a huge percentage of shared traits if people chose partners with the same traits as theirs (Vukasović & Bratko, 2015). Another assumption and caution of these studies is the equal surroundings, which asserts that identical and fraternal twins brought up in the same environment and sharing the same genetic background have a different and separate influence on a specific trait.
In conclusion, the current scheme for studying behavioral genetics depends on twins brought up in the same surroundings, which offers control for shared environment variations and genetic background in their early life. Additionally, there are different changes in the model, which might offer scientists an essential advantage as the slight change is used to accurately assess different environmental influences that affect twins over a certain period. Twin and adoption studies have been essential tools researchers use to understand behavioral genetics and determine the effect of environmental variations and genetic makeup on one’s behavioral traits.
References
Friedman, N. P., Banich, M. T., & Keller, M. C. (2021). Twin studies to GWAS: there and back again. Trends in cognitive sciences, 25(10), 855-869.
Tikhodeyev, O. N., & Shcherbakova, О. V. (2019). The problem of the non-shared environment in behavioural genetics. Behavior genetics, 49(3), 259–269.
Rimfeld, K., Malanchini, M., Spargo, T., Spickernell, G., Selzam, S., McMillan, A., … & Plomin, R. (2019). Twins early development study: A genetically sensitive investigation into behavioral and cognitive development from infancy to emerging adulthood. Twin Research and Human Genetics, 22(6), 508-513.
Vukasović, T., & Bratko, D. (2015). Heritability of personality: A meta-analysis of behavior genetic studies. Psychological bulletin, 141(4), 769.
Charney, E. (2012). Behavior genetics and postgenomic. Behavioral and brain sciences, 35(5), 331–358.
Jansen, A. G., Mous, S. E., White, T., Posthuma, D., & Polderman, T. J. (2015). What twin studies tell us about the heritability of brain development, morphology, and function: a review. Neuropsychology review, 25, 27-46.
Plomin, R., Chipuer, H. M., & Neiderhiser, J. M. (2013). Behavioural Genetic Evidence for the Importance of Non-shared Environment. Separate social worlds of siblings: The impact of non-shared environment on development.
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