Genetic Influences on Personality
The research carried out in the field of behavioural genetics has indicated, over the course of many studies, that genetic influence has a direct affect on individual differences in personality. Still, behavioural genetics has a lot to provide to the study of personality than inheritability predicts. This paper will discuss a few of the findings from research carried out on behavioural genetics in personality that go beyond the basic question; nature vs. nurture. The findings from the research include genetic continuity and environmental change during development, the impact of shared and non-shared environmental influences on personality and personality as a go-between of genetic influence on environmental measures. There are two general methods that have commonly been employed by behavioural geneticists investigating the genetic influence on personality: twin studies and adoption studies.
Recently, there has been a surplus of behavioural genetic studies in the aetiology, particularly when discussing individual differences in personality. The results conclude that ‘Most personality traits show some genetic influence’; this has now become accepted within the study personality, (Plomin, & DeFries, 1996). A very important discovery in genetic research on personality relates to the environment. It has been stated that genetic aspects are responsible for approximately 20 to 50% of the phenotypic variation in personality. The remaining variation is said to be the cause of environmental aspects. On the other hand, the study of twins and adoption find that shared family environments are accountable for only a small portion of variation in a majority of element of personality (Plomin, & DeFries, 1996).
It is important to note that there are a few aspects of this study that have grown to be quite complex. One of these aspects is the theory and research
References: Braungart, J. M., Plomin, R., DeFries, J. C., & Fulker, D. W. (1992). Genetic influence on tester-rated infant temperament as assessed by Bayley’s Infant Behaviour Record: Non-adoptive and adoptive siblings and twins. Developmental Psychology, 28, 40–47. Pedersen N. L. McClearn, G. E., Plomin, R., & Nesselroade, J. R. (1992). Effects of early rearing environment on twin similarity in the last half of the life span. British Journal of Developmental Psychology, 10, 255–267. Plomin, R. (1986). Behavioural genetic methods. Journal of Personality, 54, 226–261. Plomin, R. (1986). Development, genetics, and psychology. Hillsdale, NJ: Erlbaum. Plomin, R. (1990). The role of inheritance in behaviour. Science, 248, 183–188. Plomin, R., & Daniels, D. (1987). Why are children in the same family so different from one another? Behavioural and Brain Sciences, 10, 1–59. Plomin, R., Chipuer, H. M., & Neiderhiser, J. M. (1994). Behavioural genetic evidence for the importance of non-shared environment Plomin, R., & Foch, T. T. (1980). A twin study of objectively assessed personality in childhood. Journal of Personality and Social Psychology, 39, 680–688. Saudino, K. J., DeFries, J. C.,& Plomin, R. (1996). Tester-rated temperament at 14, 20, and 24 months: Environmental change and genetic continuity. British Journal of Developmental Psychology, 14, 129–144. Plomin, R., & Bergeman, C. S. (1991). The nature of nurture: Genetic influence on “environmental” measures. Behaviour and Brain Sciences, 14, 373–427.