Which of the following is an example of a biological factor that can influence risk for mental illness?

• A. Neurotransmitter imbalances.
• B. Sleep quality.
• C. Genetic predisposition.
• D. Social support.

Answer: (C)

Biological factors are parts of biology that can influence risk for mental illness. Genetic predisposition is a clear example because it involves inherited gene variations that raise the likelihood of developing a disorder. This baseline vulnerability is supported by family and twin studies showing higher rates among relatives, even when environments differ. The diathesis-stress model describes how this genetic risk can be triggered by life stressors, linking biology with later experiences. While neurotransmitter imbalances can also affect brain chemistry, and sleep quality or social support influence mental health through different pathways, the question highlights inherited biology—captured by genetic predisposition.