Who am I? Why do I act like this?*
We don’t know about you, but we spend an awful lot of time thinking about these questions. We often reflect on our lives and how experiences have shaped our paths. We have been taught to consider our DNA, the encoded core of who we are. For a long time, we figured these two things—genes and experiences—co-existed in our development but acted independent of each other. It turns out, though, that there’s a lot more to the story.
Philosophers and scientists have thought for centuries about this problem of nature versus nurture. They had red-hot debates about which one formed and defined a person; they wrote hundreds of essays and articles and books on the topic. As it turns out, the reality is much more complicated than the binary question suggests.
Scientists now recognize that there is quite a bit of interplay between the physical molecules of a person’s DNA and the environment she is living in. They call this epigenetics, which refers to the chemical modification of DNA due to environmental factors (Meaney, 2013). In other words, the lived experience of an individual can influence her gene behavior. It’s important to note, though, that the sequence of the DNA is not altered; rather, smaller molecules are used as “tags” on the DNA which activate or deactivate genes (Guerrero-Bosagna, 2016).
Perhaps an analogy will make this easier to understand. Let’s focus on “Sally” and pretend the entirety of Sally’s DNA is a book, filled with hundreds of pages of text. Everything is already printed when she’s born—all the words, which represent the nucleotides in her DNA, are present from her first moment of life. Each sentence in Sally’s book is a gene, a combination of words that form a code. When read out loud, this code is translated into something tangible—in cells, genes are translated into proteins that do things for the body. Additionally, Sally’s book comes with some sticky notes inserted, which make some sentences easier to find. Similarly, some pages are taped together, making other sentences hard to locate and read. These tags (sticky notes and tape) represent the epigenome in this analogy. They aren’t part of the DNA itself and they do not change the printed words; however, they do affect how easily a gene can be accessed.
As it turns out, the process of tagging DNA doesn’t only happen before birth—it continues throughout infancy and beyond (Guerrero-Bosagna, 2016). Sally’s environment and experiences changes the tags on her DNA. Sometimes, this makes genes more accessible and increases the amount of the corresponding protein; other times, a gene can’t be reached and protein production slows. Though this sounds insignificant, these changes can dramatically affect Sally’s wellbeing—if the inaccessible gene makes a protein to fight illness, for instance, Sally’s immune system will suffer.
Clearly, epigenetics matters in the scheme of our health and development. Changes to the epigenome, such as making a gene harder to transcribe, can survive cell division—in other words, it can affect a person for her entire life (Guerrero-Bosagna, 2016). This can be a very good or a very bad thing, depending on the genes involved!
As infants are constantly growing and making new cells, scientists have found it important to examine the effects of environment on their epigenome, and thus on their healthy development and well-being. Different parenting styles and actions can significantly modify a child’s epigenome, creating long-lasting alterations to their functioning (Meaney, 2013). For instance, one study found that children who suffered maltreatment showed the same chemical tag on a gene; children who did not experience abuse lacked this tag (ibid). Other examples involve the emotions of anger and fear—heightened levels of stress early in life predict “hyperaggressive temperaments” in adults (Panksepp, 2013, p. 82), while the chronic arousal of fear in infancy often leads to issues with anxiety and depression (ibid).
Epigenetic changes can be positive, too—children who receive frequent and liberal care from their parents (i.e. comforting touches and eye contact) better handle their emotions and display social, playful, and friendly behaviors (Panksepp, 2013); parents who are attentive to their babies and answer their cries help the children regulate feelings of panic and lessen their susceptibility to depression (ibid). Each of these are instances in which environmental factors cause “epigenetic changes in gene expression,” which remains with a child and affects her future well-being (Panksepp, 2013, p. 83).
Though scientists have made great progress in the understanding of the interplay between genes and environment, there is still much to learn. Plenty of questions remain: What are the periods in childhood in which the most crucial epigenetic changes occur? Are there ways to identify dangerous changes to the epigenome, and if so, what can be done to remedy them? Do medicines and other synthetic substances created with health as the goal affect our gene expression?
Regardless, it’s clear that the conversation between our genes and the environment is ongoing and has boundless impacts on our health (Guerrero-Bosagna, 2016). We should strive to create the healthiest environments possible for ourselves and our children, promoting natural and positive epigenetic activity.
References
Guerrero-Bosagna, C. [TED-Ed] (2016, June 27). What is epigenetics? [Video file].
Meaney, M. J. (2013). Epigenetics and the environmental regulation of the genome and its function. Evolution, early experience and human development: From research to practice and policy (pp. 99-128). New York, NY: Oxford University Press.
Panksepp, J. (2013). How primary-process emotional systems guide child development. Evolution, early experience and human development: From research to practice and policy (pp. 74-94). New York, NY: Oxford University Press.
*First author is Kelly Burke, a senior at the University of Notre Dame.