For you to properly enjoy the concert, a lot of little things have to come together in just the right way: from the musicians’ level of skill and acoustics of the place to your own mood at the moment. If you’ve ever marvelled at how individual instruments, tones, and rhythms combine into a beautiful symphony, you can appreciate the complicated balance of forces at work to create such a masterpiece. The same is happening inside of you – a constant exchange of information between your genes and your environment.
Nature vs. nurture
It began with the question of nature vs. nurture, which has intrigued people since medieval times. What innate or outside forces are at work to help create each facet of us complicate biological machines?
The phrase was popularized by Francis Galton, the founder of eugenics and behavioural genetics. The debate considers human behaviour as a result of either a person’s genes or his environment. The latter was termed tabula rasa or the blank slate. It means that at birth, people are blank slates and that all our behavioural traits develop exclusively as a result of environmental influences. This question sparked heated debates and drove the relentless pursuit of knowledge until scientists finally came to a conclusion: they are not mutually exclusive. They, in fact, work together and instead of nature vs. nurture, human behaviour is determined by nature and nurture.
And as science delved deeper into those intricated relationships, it became clear that those findings are not limited to behavioural traits alone.
Genes are basically an instruction manual on building a human being and keeping him or her alive. It is a code contained in the nucleus of every cell in your body. Those “genetic instructions” produce proteins, molecules essential for our very existence. They regulate a myriad of processes in our body, including determining our structure and function.
Living beings are irrevocably connected to their environment. But what exactly is the environment? It is a broad term, including every factor we are exposed to daily – and not just from the outside. When we discuss gene expression, the term environment also encompasses our cells, where genetic material is stored, and our bodies, built from those cells. Therefore we recognize the internal and external environment.
Every second our environment bombards our body with information, and our body responds. Temperature drops, we get goosebumps. We drink coffee, and we get the energy to finish our tasks. These are all examples of our environment influencing us.
The gene-environment interaction
Our genetic material, as complex and essential as it is, is susceptible to all kinds of interference. Parts of our genetic code can go missing, duplicate, occupy the wrong position, etc. All those changes influence the expression of genes and consequently, the proteins they code for. Sometimes those changes don’t have any significant results; sometimes they are beneficial and sometimes harmful.
If a phenotype (the expressed individual trait) depends on a particular environmental factor, we call it the gene-environment interaction. It can be chemical, biological, physical, behavioural, or even a life event.
Let’s consider the Sun as an environmental factor that influences skin cancer risk: individuals with fair skin (which represents one possible phenotype) are much more at risk for developing skin cancer than those with dark skin (another phenotype).
Today scientists concur that most human diseases, including common chronic conditions such as cancer, CVDs, and diabetes, are a result of the complex interaction of genetic predispositions to disease and environmental factors.
The environmental factors with the strongest influence on the development of diseases include chemicals, nutrition, behaviour, physical surroundings (environmental and psychological), and infections. Many of those are within our power to adjust or change, providing us with effective protection.
Let’s return to our concert analogy: our genes are like musical notes. They hold potential for a great concert, but notes alone don’t make music. It must be brought to life by musicians, my many different people with different skills, all led by a conductor who translates the notes into music you enjoy.
To make sure your symphony is played without errors, you need to know the notes. And a DNA test reveals them as genetic predispositions, which give you the power over the aspects of the environment you can change, employing both nature and nurture to help you carve a path to longevity.