If you believe that your personality is influenced by your genes, you may be surprised that there is no simple answer to the above question. Personality traits are complex and research suggests that they are shaped by both inherited and environmental factors that interact in a variety of ways to form our individual personalities.
Early studies
Early studies into genes and personality examined self-reports of personality or compared self-reports of fraternal twins who share about 50% of their genes to those of identical twins who share 100% of their genes.
This early work clearly suggested that there were genetic influences on personality. Of course, the next question researchers began asking was which genes were responsible.
Defining genes and a genomes
In the nucleus of each cell in your body are 23 pairs of chromosomes. One of each pair comes from your father, and the other from your mother. Each chromosome is made up of strands of deoxyribonucleic acid (DNA).
DNA consists of segments called genes. A gene is a basic biological unit of heredity that transmits characteristics from one generation to the next.
What is a genome? A genome refers to your whole collection of genes, an estimated 20,000 to 30,000.
Candidate genes
Researchers have been trying to find out the influence of certain genes on personality for decades and many of them have been disappointed with the results. For example, promising candidate genes, like the MAOA gene, linked to antisocial behavior in previous research, did not replicate in subsequent work.
No single gene influences personality
Current prevailing genetic evidence suggests that we don’t have genes for personality. This isn’t for lack of trying as millions of dollars have been spent on research of this nature.
However, earlier decades of twin research showing similarities in personality between identical twins can’t be ignored. Perhaps it is simply that a different approach to research is necessary.
Is it influenced by a complex system of genes working together?
In a 2010 study, J. Derringer led researchers in an examination of a collection of single nucleotide polymorphisms (SNPs) associated with dopamine in prior research. They then looked at associations between these SNPs and sensation-seeking behavior which is linked to behavioral disorders such as addiction.
What was different about this research was that instead of looking at genes and personality in a one-to-one relationship, researchers looked at a complex system of genes working together to express a specific personality trait.
The results still didn’t come anywhere near what the twin studies that suggested – that 40% of identical twin personality was genetic.
Personality does not seem to be determined by any single gene, but it is possible that the actions of many genes working together may influence it. However, even when they’re working together, this does not explain everything.
Some genes may increase a certain characteristic whilst others may decrease it. The final result appears to come from a complex relationship among various genes, as well as a variety of random factors.
Environmental influences
Largely unknown environmental influences may have a great impact on personality. Because these differences are largely random, we do not inherit our personalities in any fixed sense.
Genetic differences that may exist at birth are often amplified or diminished over time through environmental factors. Even genetically identical twins develop distinct personalities, largely as a result of environmental factors.
Genetics is important and every day we learn more about its role in personality variables. However, our personalities don’t depend on genetics alone. Differences in brain structure, upbringing, nutrition, education and even in the ways genes interact is what makes us into unique individuals.