Humans are complex beings, with their personalities and behavioral patterns being perhaps their most intricate aspects. The fascination with this aspect of human behavior can be seen in popular debates such as Nature v.s. Nurture, or in social theories such as the Bouchard Twin Study. Social psychology scientists have long studied human behavior and whether we are the result of our biology or our environment, aiming to answer the question "Is personality genetic?".
If our personalities result from genetics, then we develop them early on and will remain the same throughout our lifetime. However, if they are a result of our environment, then our personalities may evolve throughout our lifetime, and our experiences will have a more significant effect on them. Studies have concluded that human personalities and temperaments are shaped by both genetics and our environment; while we may be born with certain personality traits, there still is the possibility to develop others as we experience life.
Often, a person might seemingly inherit their parent’s short temper or perfectionist tendencies. That same child may inherit their parent’s big blue eyes and thick curly hair. While it may be clear that the physical characteristics are genetic correlations, it is difficult to know whether the behavioral traits result from genetics or learned thanks to years of exposure throughout childhood.
Personality traits like openness to experience or intimacy seem to be shaped by a child’s upbringing. In contrast, more stable characteristics like distractability or agreeableness seem to be rooted within a child’s DNA. You may wish to take a personality traits test to determine your personality type and behavioral characteristics. Specific characteristics are associated with different genomes, making them reliant on genetics, and other features may be developed later on due to external factors. While it is understandable to assume that personality is the result of genetics, it is important to consider that personalities are hereditary and a result of environment or other factors.
Multiple variables shape our traits, genetics being one of them. In fact, a study found that 20%-60% of our temperament is determined by genetics. They also found that specific primary genes are involved in the communication of cells within the brain, which directly affect someones' personality and behaviors. Possessing certain genes can significantly impact sociability, predisposition to anxiety or depression, self-control, and more.
The same study suggested that while our personality traits may evolve as we grow into adulthood thanks to life experiences and events, our core temperament generally remains the same. This suggests that at our core temperament, we are made up of specific traits that have genetic components.
Temperament is usually associated with heritability and includes common behavioral traits that influence how we do things--such as being persistent or shy. Subsequently, personality is generally associated with why we do things--like openness to experience or agreeableness-- and is shaped by our genetics and upbringing.
If genetic variants comprise only 20%-60% of our personality, where does the other portion come from? Environmental factors, such as upbringing, culture, geographic location, and life experiences, greatly influence our personality. For example, a child raised in a harmonious environment may have a more positive or calm outlook and disposition. In contrast, a child raised in a turbulent household may be more inclined to develop aggression or other adverse traits.
Proving this theory further is the famous Minnesota Study of Twins. From 1979 to 1999, researchers studied both identical and fraternal twins separated at birth to determine the effects of genes and environment on their personalities as they aged. This study found that identical twins shared about 50% of the same traits, whereas fraternal twins shared about 20%. The study also found 70% of the variance in IQ was linked to genetic variations, while the remaining 30% was due to environmental effects.
In studying different pairs of twins and their genetic differences and aspects of personality, scientists also found that while these genetic effects greatly influence personality, other factors such as leading a healthy lifestyle and engaging in intellectual activities played a great role in their overall well-being and development.
Here are some of the environmental influences that can affect personality characteristics and development:
Culture is defined as the shared values, customary beliefs, traditions, and social norms of a group. It is perhaps one of the most powerful drivers in individual differences and personality dimensions. For example, someone raised in an individualistic culture may value independence or personal success. In contrast, someone raised in a more collectivist culture may value social harmony and the group’s needs over their own.
Similar to culture, geographic location directly impacts human behavior. Depending on your location, you are exposed to different experiences, hardships, cultures, and more. For example, in a fascinating study, 1.5 million people across the United States were evaluated based on personality characteristics. The study found three distinct regional personality differences across the country:
Cluster 1: The Upper Midwest and Deep South are mainly comprised of people with a "friendly and conventional personality.”
Cluster 2: The West is mainly comprised of people who are relaxed, creative, calm, and emotionally stable.
Cluster 3: The Northeast is mainly comprised of people who are people who are exposed to more stress and therefore more likely to experience irritableness or depression
Within a geographic location and culture, smaller groups called communities form. These communities are generally people who live in the same place and share certain traits, goals, or interests. Community influences could include role models, religion, and neighborhood context. For example, a theory conceived by RJ Sampson called "Social Disorganization Theory" suggests that when people live together in a community, emergent properties develop: characteristics that cannot be predicted from the individual characteristics of the residents. Meaning, that personality development for a community as a whole is actually impacted by its' residents. Therefore, the link between community and personality is quite strong.
Another environmental factor that plays a role in personality characteristics is the schools people went to and their education. Studies found that various school experiences were associated with personality changes. For example, a student who prioritizes studying and doing their homework may experience an increase in conscientiousness. In contrast, a student exposed to a stressful or volatile school environment may increase neuroticism.
While there are endless possibilities for how a person behaves and perceives the world, five primary traits are often measured. Personality models such as The Big Five measure agreeableness, openness, extraversion, neuroticism, and conscientiousness. From these main characteristics, a personality type can be determined. While environment certainly plays a role in personality development, genetic influences tend to have an even more significant effect. Through family studies and genetic studies, many genes and resulting behavioral traits have been found to be directly linked to heritability. Here are some other inherited personality traits:
Specific learning disabilities resulting from high levels of distractibility, such as ADHD, have been found to be linked to numerous inherited genes. Unfortunately, there are no genetic tests to determine whether someone has ADHD; however, after nearly 2,000 studies, it has been found that the genes typically linked to ADHD often run in families. Usually, if a person is easily distracted and diagnosed with a condition such as ADHD, another blood-relative or parent also having it is very likely.
In a newer study, specific inherited DNA sequences were found to correlate with leadership abilities. In this study, a particular genotype was found associated with passing leadership abilities down through generations. While leadership may still be thought of as a skill to have or develop, it is important to note the role behavioral genetics plays.
During the Minnesota twin studies, scientists found that certain traits, including neuroticism, were inheritable. People with this trait are more vulnerable to stress and are often seen as more nervous and sensitive to stimuli, while those without may have a more positive and calm demeanor. Doctors theorized that people with higher levels of this trait could potentially benefit from therapy, although a life of low stress would be most beneficial.
The environment in which a child is raised can influence their level of patience and reaction to stressors. A study measuring the patience of children abroad found that those residing in more remote and rural locations tended to be more patient than those living in more industrialized city locations. The ability to be patient and tolerant of uncertainty varied significantly based on the location, suggesting that the environment greatly influenced this trait.
Another trait measured during the Minnesota twin studies is the need for intimacy, which seems to be more based on the environment rather than genetics. Researchers found that two-thirds of this personality trait depended on past experiences. Someone raised in an unloving or individualistic environment may have low amounts of this trait- meaning they tend to keep to themselves and do not have a strong desire to be in emotionally intense relationships or situations. Doctors also stated that this gene, in particular, can be greatly strengthened through quality interactions with family; this trait will develop more in children exposed to emotional and physical intimacy during adolescence.
People within different communities or cultures will have contrasting practices when it comes to manners and etiquette. A polite person who practices good manners typically will have had a different upbringing than a person who acts oppositely. Certain standards of decorum, acceptable behaviors, and morality result in a learned expression of how a person behaves in different settings. For example, in American culture, it is polite to say "please" and "thank you" and to send "thank you" letters after receiving a gift. In Spain, it is polite to greet others with a kiss. Etiquette varies depending on culture and therefore has differing effects on personality development.
The common debate, nature-vs-nurture, questions whether humans are a result of their genetics or their environment. Various studies have found that the multiple aspects of personality result from specific genes and environmental effects. Although many of our personality traits may evolve as we grow and experience life, our core temperaments and characteristics remain relatively consistent.
While environmental influences undoubtedly play a role in shaping our personality, how we behave is primarily determined by genetics. Learning about your own personality type can help you better understand your inner workings and behavioral patterns.
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