Final answer:
Disorders such as depression, schizophrenia, and ADHD are examples of multifactorial genetic disorders, which involve a complex interplay of genetic and environmental factors that contribute to their development.
Step-by-step explanation:
Disorders such as depression, schizophrenia, and attention deficit hyperactivity disorder (ADHD) are believed to result from the interaction of many genes with environmental influences. These are examples of multifactorial genetic disorders. Multifactorial inheritance means that "many factors" are involved in causing a health problem. The factors are usually both genetic and environmental, where a combination of genes from both parents, in addition to unknown environmental factors, produce the trait or condition. Often one gender (either males or females) is affected more frequently than the other in these disorders. As seen in ADHD, disturbances in neurotransmission and perhaps exposure to certain pesticides may contribute to the development, which shows the complex interplay of nature and nurture.
Similarly, schizophrenia involves genetic vulnerability and environmental stress, indicating that both factors are essential for the disorder to manifest. In the case of major depression, the underlying causes are also believed to include both genetic susceptibility and environmental triggers, with neurotransmitter imbalances playing a significant role.