Fiona Williamson
Mr. Perez
Psychology
February 22, 2023
Scientists have been debating the question of whether the traits of people are
primarily determined by genetics or by their environment for centuries. On one side of
the argument, the nature theory proposes that who we are is determined from birth via the
genes that get passed down from our parents. On the other side of the argument, the
nurture theory maintains that our traits develop as a result of exposure and what we learn
from our environment. From the cases presented by scientists on both sides and the
evidence that I have collected from my own experiences, I believe that nature has a
greater impact in determining who we are.
Advancements in the field of genetics have revealed that we not only inherit
physical characteristics from our parents, such as eye and hair color, but also behavioural
traits. In studies comparing biological and adoptive siblings, J. Neill observed, “In many
cases, it has been found that genes make a substantial contribution, including
psychological traits such as intelligence and personality.” My own experiences reflect his
findings. In my extended family, there are several people who have been adopted. When
you compare their characteristics to members of the family who are biologically related,
they tend to be extremely different and experience greater life struggles similar to their
birth parents, despite having lived their entire childhood with our family. Behavioural
genetic studies involving twins also conclude that their environment does not
significantly impact who they become. Robert Plomin wrote, “Like identical twins who
were raised together, identical twins who were reared apart from birth tend to be similar
in behavioral and psychological traits.”, suggesting that genetics is the main driver since
they would have identical genes. Researchers now believe that genes influence mental
illnesses, and according to Roni Dengler with science.org, “the global Psychiatric
Genomics Consortium found that people with autism, schizophrenia, bipolar disorder,
depression, and attention-deficit hyperactivity disorder frequently share certain DNA
variations.” I believe that if these psychological traits can be tied to genetics, then other
personality traits, such as anger and sensitivity, are likely tied to genetics as well. Robert
Plomin in Scientific American also argues that our genetics actually influences our
environment since it is not independent of us. He says that “we select, modify and even
create our environments in line with our genetic propensities”. This strengthens this
notion that our innate nature impacts us the most.
While evidence from sibling studies and research into mental illnesses reveals that
genetics plays the largest role in shaping people and who they will be, other evidence
shows that it cannot be the only answer. Clearly there are life experiences that can direct
people’s lives in different ways and there is a random variability affecting expressed
traits. Until the answer can be completely formed, scientists will continue to debate this
issue. People inherently want to know about themselves and others. Knowing why we are
the way that we are can guide us in our search to become better people and give us a
greater understanding of ourselves.