Final answer:
Paul's sister's diagnosis with paranoid schizophrenia primarily relates to both Psychology (as schizophrenia is a psychological disorder) and Genetics (since there is a strong genetic component to schizophrenia risk). However, environmental factors also have a significant role.
Step-by-step explanation:
The situation of Paul's sister being diagnosed with paranoid schizophrenia relates primarily to both Psychology and Genetics. Schizophrenia is a psychological disorder that can have significant impacts on thought, perception, emotion, and behavior. It is typically first diagnosed during early adulthood.
However, Genetics also plays a significant role. Research has indicated a strong genetic component to schizophrenia. For instance, one's risk of developing schizophrenia increases if they have a parent or sibling with the disorder. Studies involving adoptees have also shown that those born to mothers with schizophrenia have a higher risk of being diagnosed with the disorder themselves.
Nevertheless, it's important to mention that while genetic predisposition can increase susceptibility, it doesn't guarantee the development of the disorder. Environmental factors, such as stressful life events, also contribute significantly and interact with genetic factors. Paranoid schizophrenia thus likely results from a combination of genetic predisposition and environmental triggers.
Learn more about Schizophrenia