The influence of our genes on our personalities is a fascinating and hotly debated subject in psychology. It’s a question of nature versus nurture – a phrase was coined in 1969 by Psychologist Sir Francis Galton who used it to describe the impact of genes versus environmental influences. Our physical appearance and our health are undeniably influenced by both. We can inherit blonde curly hair and blue eyes from either parents (nature) and our environment, whether it’s a polluted city or a seaside town, can impact our respiratory health in the long term (nurture). But can the same logic be applied to our personalities?
Genes are around 99% the same in each human being. These common genetic structures mean that members of the same species have behaviours and characteristics that define them – known as instincts. These complex yet innate patterns of behaviour ensure survival and reproduction. Birds sing at daybreak, rabbits burrow in the ground and humans learn to walk, speak and understand language. But the strength of traits between species varies. Some rabbits are more fearful than others, some dogs like to lie in on the weekend, and others are driven to chase sticks around at 100mph. These differences occur in humans too – the 0.1% difference in genes produces a unique set of traits and characteristics that make human beings the individuals that they are.
But do we inherit all our characteristics from our parents, or do we change in response to the way that we live our lives? If we look at the argument for nature, it suggests that our personalities form early in our lives and are difficult to change. If we argue for nurture, then it’s our experiences that are important, suggesting that our personalities evolve as time goes on.
Some geneticists estimate that as much as 60% of our personality is determined by genes. However, there is no IQ gene that determines intelligence, no kindness gene that determines whether a child will bully another. But rather there is a complex relationship among the various genes. Some genes work to increase characteristics, and others will decrease those same characteristics. The largest breakthrough in genetic research the past few years is polygenic testing. This is able to correlate multiple genes – often thousands – with behaviour differences. Using polygenic testing, we can identify genes such as great leadership quality, vulnerability to stress and nervousness and even distractibility.
Genetic factors also always work in tangent with environmental factors. For example, our upbringing, culture, geography and life experience can all greatly influence our personality. For example, one study into regional personality types in America identified three clusters:
- Cluster 1: The Upper Midwest and Deep South were associated with personality types that comprised people of a "friendly and conventional nature.”
- Cluster 2: The West is mainly comprised of people who were relaxed, creative, calm, and emotionally stable
- Cluster 3: The Northeast was mainly comprised of people who are people who were exposed to stress and therefore more likely to experience irritableness or depression
However, extent to which we are influenced by our biology is disputed. A number of large-scale twin studies suggest that we are largely determined by our biology and not our environment. The Minnesota Study of Twins Reared Apart studied 350 pairs of twins between 1979 and 1999. The results revealed that the personalities of twins, whether they were raised separately of apart, displayed similar personality traits to their biological parents.
The nature versus nurture argument is certainly rich and complex, and always ongoing. If you want to learn more about how your genetic makeup influences your personality, our Whole Genome Test can reveal all.
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