Introduction
Heritability of personality is one of the most contentious issues in the field of modern psychology. There is no denying that one’s personality is influenced by their genetics. However, there is also a relative consensus that not all personal characteristics are determined by genetic factors. Understanding what evidence is used to prove the connection between genetics and personality is essential in ascertaining the validity of such conclusions. Overall, the most common evidence used to prove the heritability of character traits is data derived from twin studies. After all, twins have nearly identical DNA and share more similarities with each other than other related people. Overall, the use of general personality characteristics in the analysis of twins compromises the reliability of evidence.
Discussion
The major argument made for the importance of genetic factors was that twins who were separated at birth exhibited similar personality traits. Actually, there were numerous studies that made such observations, starting in 1937 at the University of Chicago, and then in 1968 at the Institute of Psychiatry at the Maudsley Hospital (Tarnoki et al., 2022, p. 140). These were followed by more studies, some of which are still being conducted. In all cases, there was a definite similarity between personality traits. Despite the fact that twins lived different lives and had different backgrounds, they still developed personalities that were not significantly different from each other. This implies that genetics plays an important role in determining personal traits.
The major problem with these data is the degree of similarity. Not a single study reported a twin pair that would exhibit total resemblance. Some studies observed up to 75% of similarities, while the majority leaned toward 50% (Tarnoki et al., 2022, p. 141). Furthermore, there were several dimensions used to evaluate the differences in personality. For instance, neuroticism, extroversion, and other character traits were assessed differently. The result was the average, which means that there could have been stark resemblance in some personal characteristics, but little similarities in others. The subsequent implication is that there is no certainty on whether genetics influences people’s personality. In essence, the resulting constituency of character has a 50% probability of resembling one’s parents.
As a consequence, genetics is both relevant and not that significant in determining personality. The evidence for resemblance was drawn from the analysis of general personal characteristics. However, it misses the possibility that personality types are actually not that multivariate. Actually, it is entirely possible for completely unrelated individuals to have a high degree of resemblance despite sharing no DNA. Twin data also supports this, as many twins are different from each other in every aspect except for physical (Tarnoki et al., 2022). This means that genetic factors are not decisive in the formation of one’s character.
Conclusion
In conclusion, the reason why evidence for the heritability of personality is insufficient lies in the ambiguous data that can be interpreted differently. Most studies report 50% similarities between the character features of twins. 50% resemblance may also mean that there is a 50% divergence in personality. Furthermore, although the overall makeup of each individual’s character is unique, personality traits that people can exhibit are limited. As a result, analysis of unrelated individuals may yield stark similarities in personality. Meanwhile, fraternal twins may have different characters despite sharing the same DNA. The only reasonable explanation is that genetic factors do influence what personality one can develop, but they are by no means definitive.
Reference
Tarnoki, A. D., Tarnoki, D. L., Harris, J. R., & Segal, N. L. (Eds.). (2022). Twin research for everyone: From biology to health, epigenetics, and psychology. Elsevier Science.