Na(Nur)ture
- Liya Zhang
- Jun 10
- 8 min read
Updated: Aug 6
When we consider the notorious horror tale of Frankenstein, we must ask ourselves: was the creature born into monstrosity and craved vengeance, or was it the very environment of abuse and isolation imposed by its own creator that shaped its fate? This very debate of nature versus nurture resonates in both real-life and literature. Nature suggests that our behaviors are hardwired within us, while nurture emphasizes the influence of our upbringing in shaping who we become. This ongoing discussion in the field of biology raises a compelling question: so what truly shapes our identity–our inherent traits or the environment in which we were raised?
Nature is all that a man brings with himself into the world; nurture is every influence from without that affects him after his birth. Francis Galton, 1874
Tracing the Roots
The Nature vs. Nurture debate traces its roots back to Sir Francis Galton, a prominent figure in the late 19th century and cousin to the famous “father of evolution”, Charles Darwin. In 1869, Galton authored Hereditary Genius, the book that would begin the investigation of inheritance (Katch, 2022). The idea that intelligence, health, and potential were determined by genetic background gained traction at the time. People began thinking that everything – from moral character to intelligence – was stamped into our genes and passed down through generations like an ancient family heirloom.
Around the same time, French scientists began experimenting with ways to test children’s readiness for school, unknowingly sparking a wave of psychological studies into the inheritance of “learning abilities”. At the time, society had largely accepted the idea that heredity was the basis of one’s intelligence and place in social order (Katch, 2022). This belief became a suitable justification for social hierarchies and inequalities.
Enlightenment philosophers such as John Locke, the “father of liberalism”, and Jean-Jacques Rousseau challenged these genetic theories. They argued that people were all born as tabula rasa, or “blank slates” (Katch, 2022). To them, intelligence wasn’t a genetic inheritance, but something developed by experiences and atmosphere. Their perspective connects to the ideas of modern scientists who argue that our childhood experiences and environmental influences are far more crucial in shaping who we become than any genetic makeup.
Neurogenesis & Neuroplasticity
Long before the advancement in neuroscience, scientists once thought our brains were fixed machines – pre-programmed with a finite number of neurons, hardwired and unchanging. They believed we were born with a certain design, and as we grew, our neurons would eventually fade away, leaving us with a deteriorating mind at the time of our deaths. By the time we reached the end of our lives, our brains would be little more than a shadow of what it once was (National Academy of Sciences [NAS], 2008).
Geneticist Fred Gage made a groundbreaking discovery in 1998: the human brain is capable of creating new nerve cells well into adulthood. Through experiments with mice, Gage showed that the rate of neurogenesis – the process in which new neurons are created in the nervous system – increases in response to external factors, proving that our brains are far more adaptable than we previously thought (NAS, 2008). The debate of nature against nurture dramatically shifted as it became clear that both factors play a role in shaping the most complex area of our bodies.
As research into neurogenesis and neuroplasticity progressed, scientists discovered that the brain is constantly changing as it has abilities to form, strengthen, or eliminate neural connections through experience. This led to a further understanding of how the brain operates, with a “use it or lose it” principle; the more frequently a neural pathway is stimulated, the stronger the connection becomes. Likewise, if a connection goes unused, it weakens or even breaks.
Our entire neural system operates as a feedback circuit; our experiences shape brain activity, which is then going to influence how we interact with the world. For example, let’s take a fascinating experiment with mice to illustrate this idea. Research has shown that when a mouse’s eye is taped shut from birth, the neurons responsible for vision in that eye are never stimulated. The neurons have ultimately failed to develop properly. Consequently, the animal will never be able to see from that eye. On the other hand, if the eye of an adult mouse is taped shut, its vision is unaffected (NAS, 2008). This is because the appropriate neurons had already been activated and strengthened through experience earlier in life, emphasizing how important stimulation is for brain development and function.
Furthermore, genetic programming is critical in the formation of synapses, which are the gaps between nerve cells where communication occurs. However, it’s important to recognize that while genetics determine the initial creation of synapses, their strength and longevity depend solely on how often they are stimulated. Ultimately, the brain’s structure is framed not just by its genetic blueprint, but by how actively we engage with the world around us.
Twin Research
Beyond mice, twin research has been another significant aspect to the center of the debate. Thinking back to Galton, he was the first to systematically study twins and distinguish the roles of heredity and environment in human development. This popular belief in the dominance of heredity not only incited widespread interest in genetic inheritance but also laid the foundation for eugenics – a controversial field aimed at arranging the human race by encouraging the reproduction of individuals with “desirable” traits and discouraging those with “inferior” ones.
While Galton’s conclusion has since been debunked, research on twins persists as a powerful tool for understanding the interplay between experience and genetics. According to Katch (2022), identical twins share 100% of their genes, making them genetically identical; fraternal twins, much like regular siblings, only share about half of their genetic makeup. These distinctions allow scientists to study how much of a role heredity plays in everything from health conditions to behavioral traits. Thanks to twin registries, researchers have the opportunity to track twins throughout their entire lives. Notable registries such as The Swedish Twin Registry and The Twins UK Registry collect large amounts of data, allowing studies on a range of health issues, including cancer and cardiovascular diseases (Katch, 2022).
Studies on separated twins, both identical and fraternal, have provided insights into the influence of genetics and environment on behavior and personality. These findings, along with data from twin registries, are not only strengthening our understanding of genetic factors in various health conditions but also fueling the ongoing debate about the influence of nature versus nurture.
Epigenetics
One of the most fascinating areas of the nature vs. nurture debate lies in the realm of the “changes to genetic sequences.” This is where epigenetics comes into play—a biological field of study that focuses on how genetic activity can be modified without altering the fundamental DNA sequence. Epigenetics is at the heart of understanding how behavior and environment can influence each other, sometimes working together, other times in opposition. Unlike genetic changes, epigenetic changes determine which genes are activated, playing a crucial role in shaping an organism’s traits and responses.
Gene expression is the process by which the instructions encoded in DNA are read to create proteins. This process occurs in two main stages: transcription, where the DNA code is copied into RNA, and translation, where the RNA is used to build proteins. Gene expression must be tightly regulated, as it allows cells to adapt to changing environments and maintain balance. Gene expression essentially acts as an on or off switch to control which proteins are produced at a certain time and how many.
Epigenetic changes play an incredibly important role in how genes are read and expressed, driving remarkable differentiation that takes place within our cells. While every cell in the body contains the same DNA, they function very differently–whether as muscle cells, skin cells, or countless other types.
But how does this diversity happen? The answer lies in epigenetics, which acts as the main regulator of the process, turning specific genes on or off to shape a cell’s specialized job. Through cell differentiation, an egg cell can evolve into many specific cell types, each with unique proteins and growth patterns, all thanks to epigenetic modifications. Key mechanisms involved in this process include DNA methylation, histone modifications, and non-coding RNAs.
DNA Methylation: the addition of a methyl group to DNA that effectively silences certain genes. This restricts the activation of these genes, thereby regulates cell growth and ensures the deactivation of specific genes.
Histone Modifications: Histones are the proteins that DNA tightly winds around to form chromatin (the structure that makes chromosomes). Chemical modifications to histones, such as acetylation or methylation, can alter the structure of chromatin. This allows the DNA to be more or less accessible for gene expression.
Non-coding RNAs: Small classes of non-coding RNA can bind to a mRNA during the gene expression process. This can result in the controlling of genes that will affect which genes will be translated into proteins.
These chemical marks determine how much of a gene is expressed. Together, the chemical changes form what is known as the “epigenome”–a collection of molecular tags that represent a regulator. The collection of these chemical marks is known as the “epigenome”. The epigenome is not fixed and can be reshaped throughout a person’s life. Different experiences and lifestyle choices can add or regroup these chemical marks, resulting in distinctive epigenetic patterns in each individual.
Epigenetic changes are dynamic, adapting in response to shifts in behavior or the environment. Epigenetic changes are evident in various sciences, from the differences between smokers and non-smokers to the influence of a pregnant woman’s actions on her baby’s development. For instance, when someone quits smoking, their body can begin reactivating genes that were suppressed by smoking, potentially to levels similar to those of non-smokers. Additionally, a pregnant woman’s lifestyle choices–such as diet and exercise–can shape the baby’s epigenome long before birth. Factors such as malnutrition, drug exposure, or stress during pregnancy or childhood can leave marks on brain development through epigenetic modifications. These early experiences can affect a child’s physical and mental health, potentially impacting their behavior in the long term.
Studies suggest that epigenetic inheritance is possible, meaning a parent’s life experiences can alter their epigenetic makeup and even be passed down to the next generation. This can lead to generational changes in the epigenome, influencing traits such as behavior and can potentially result in generational trauma. Both positive and negative experiences leave a stamp on our genes, whether they be temporary or permanent. This emphasizes the significance of fostering positive and healthy environments, as these experiences can shape our genetic expression and ultimately, our functioning as human beings. In fact, epigenetics reveals that the age-old debate of nature versus nurture is not an either/or scenario—it’s both.
The Balancing Forces of Nature and Nurture
The debate between nature and nurture is not about choosing one over the other but recognizing the intricate interplay between both. Our genetic makeup provides the foundation, but it is the environment—our experiences, relationships, and surroundings—that shapes how these genes are expressed. Neurogenesis, epigenetics, and twin studies have shown us that our behaviors, choices, and life circumstances can influence our genetic expression, demonstrating that nature and nurture are deeply interconnected.
Rather than being opposing forces, they work together, each influencing the other in a fluctuating, continuous process. Understanding this balance is crucial for addressing issues related to health, behavior, and development, ultimately leading to a more complete approach to human growth and potential. So really, Frankenstein’s creature and his monstrosity wasn’t just etched into its design, it was also sculpted by the cruelty it endured. The creature’s nature was built as much on the harshness of its surroundings as on its origins.
Bibliography
Institute of Medicine (US) Forum on Neuroscience and Nervous System Disorders. (2008). Grand Challenge: Nature Versus Nurture: How Does the Interplay of Biology and Experience Shape Our Brains and Make Us Who We Are? https://www.ncbi.nlm.nih.gov/books/NBK50991/
Katch, V. (2022, December 16). Nature vs. nurture? It’s both. Michigan Today.
Epigenetics and Child Development: How Children’s Experiences Affect Their Genes. Center on the Developing Child at Harvard University. (2019, February 19). https://developingchild.harvard.edu/resources/infographics/what-is-epigenetics-and-how-does-it-relate-to-child-development/