Mental Illness: Genetics or Environment?

Mental Illness: Genetics or Environment?

By: Isabelle Siegel

The term “Nature vs. Nurture” describes an age-old scientific debate regarding whether behavior, personality, and other individual characteristics are the result of nature—one’s biology and genetics—or nurture—one’s environment and upbringing. The development of mental illness is a prime example of the Nature vs. Nurture debate, as scientists and others seek to understand: Is mental illness caused by genetics or environment?

The Big Question. Is Nature or Nurture responsible for mental illness? This is essentially a trick question, as both Nature and Nurture contribute to the development of mental illness. In fact, it is ultimately the interaction between one’s genes and one’s experiences and environment that leads a person to develop a mental illness. According to the Diathesis-Stress Model, genetic predispositions develop into mental illnesses when they are met with stressful environments and/or experiences. For example, a person can be born with a genetic predisposition for depression, but that person may not develop depression unless they experience stressful environmental events such as abuse.

Nature. What are the biological and genetic causes of mental illness? It is well-documented that mental illness can be hereditary, or passed on within families. For example, a person is four to six times more likely to develop Bipolar Disorder if someone in their family has or had Bipolar Disorder. Another potent biological factor contributing to the development of mental illness is brain anatomy and brain chemistry. Research suggests, for instance, that people with schizophrenia have less active prefrontal cortices (the area of the brain associated with decision-making, planning, and personality). Other biological factors implicated in the development of mental illness include exposure to infection or toxins, damage during pregnancy, and use of substances.

Nurture. What are the environmental causes of mental illness? The development of mental illness can often be associated with one’s childhood experiences. Exposure to abuse is a potent example of an environmental factor that can lead to mental illness. Other experiences can also result in the onset of mental illness, including death, divorce, and/or other forms of grief or trauma.

In conclusion, neither Nature nor Nurture is solely responsible for the development of mental illness. Rather, genetic and biological factors combine with environmental and experiential factors to result in the onset of mental illness. 

If you or a loved one needs support for mental illness, the licensed psychologists, psychiatrists, psychiatric nurse practitioners, and psychotherapists at Arista Counseling & Psychotherapy can assist you. Contact our Paramus, NJ or Manhattan, NY offices respectively, at (201) 368-3700 or (212) 722-1920 to set up an appointment. For more information, visit

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