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Heritability Week 2 DQ 2
Heritability is the relative contribution of genes to people’s behavior and personality. It is the amount of variance observed in behaviors among people and explained by genetics (Dabandata, Bell, Nsimi, Ngalle, Bille & Nkeng, 2012). One of the major goals of behavioral genetics is the identification of the hereditability of a particular behaviour. Various methods are adopted in determining hereditability in humans. This paper delineates on some of the strengths and weakness of methods used in determination of heritability among humans, which include adoption, twin studies, and shared and unique environmental factors.
Twin studies are considered essential tools in behavioral genetics. The study uses data collected from adopted siblings and pedigrees. Such studies are important because they allow studies to be conducted in varying environments across different pairs that have different genetic makeup. Identical twins share their genes 100% (Magnavita, 2012). The differences between identical twins arise due to different experiences they go through. They are therefore able to provide realistic results concerning their personality and behaviors. Furthermore, studies have revealed that genetic contribution or heritability can account for 50% of the variance in personality (Goleman, 2006). Therefore, these studies are reliable and can be used to determine or approximate the variations for differences in traits of twins such as impulsivity and aggressiveness when compared with others.
Behaviors exhibited by people are determined by many factors in their environment. The limitation of these studies includes difficulties in accounting for 10% of the variations in specific traits (Ivanov, Mataix-Cols, Serlachius, Lichtenstein, Anckarsäter, Chang, Gumpert, Lundström, Langström & Rück, 2013). The strength of the studies includes providing informative ways of examining how hereditability and environment relate and interact. It has also helped to provide insights on the behaviors and personalities that manifest among identical twins, non identical twins, siblings, and unrelated individuals.
Genetic studies have also helped researchers understand how environment shapes the personalities of people. Since 50% of variance in personality is determined by genetic factors, it therefore means that the remaining 50% is shaped by environmental factors (Goleman, 2006). Environmental factors include shared and unique facts. These factors include family systems, infant attachment experiences and socio-cultural factors among others. They interact with genetically influenced factors in shaping people personalities. Shared environmental factors refer to parenting styles and social class assumed to be common for all children in a family (Ivanov, Mataix-Cols, Serlachius, Lichtenstein, Anckarsäter, Chang, Gumpert, Lundström, Langström & Rück, 2013). When a parent dies, it affects all the children and this can be categorized as shared environmental factor.
Therefore, one of the strengths of adopting shared and unique environmental factors in the study of hereditary is that it helps in understanding the personalities and the behaviors of an individual (Mikko, 2011). People will learn new forms of behavior and develop personality through the experience and exposure they go through over time. An individual who is brought in a family where people fear God is likely to grow up holding different beliefs than those that are raised in another setting. Therefore, this method is reliable. Limitation of the environmental factors in study of heritability is that they are subjective and may not be able to provide sufficient evidence of an individual’s behaviour and personality. Environment keeps on changing and this hampers its effectiveness as a good measuring tool.
In conclusion, genetics has made it possible for people to study behaviors and personalities of people. Various methods such as twin and shared environmental factors have been used in these studies. Even though the methods have some weaknesses, they have proved to be beneficial in understanding the behaviors and personalities of people. Twin study is one of the best methods used to study genetic behaviors of people, especially in identical twins; by contrast, shared environment has been instrumental in finding out how the environment contributes to personality of a person.

Peer reviewed from Ashfold library
Dabandata, C., Bell, J., Nsimi;M., Ngalle, A., Bille, H., & Nkeng, N. (2012). Heritability and correlations study in Okra [Abelmoschus esculentus (L.) Moench], Continental Journal of Agronomy, 6(1):24-29.
Ivanov, V., Mataix-Cols, D., Serlachius, E., Lichtenstein, P., Anckarsäter, H., Chang, Z., Gumpert, C., Lundström, S., Langström, N., & Rück, C. (2013). Prevalence, Comorbidity and Heritability of Hoarding Symptoms in Adolescence: A Population Based Twin Study in 15-Year Olds, Christian. PLoS ONE, 8 (7): 1-7
Mikko , S. (2011). On statistical methods for estimating heritability in wild populations, Molecular Ecology, 20(7):1324-1332.
Others
Goleman, D. (2006). Social intelligence: The new science of human relationships. New York: Bantam Books.
Magnavita, J.J. (2012). Theories of personality. San Diego, CA: Bridgepoint Education, Inc.