Final answer:
The risk of developing schizophrenia for a 22-year-old male whose brother has schizophrenia is higher than the general population risk, with genetics and environment both playing roles. However, an exact risk percentage cannot be determined with the provided information.
Step-by-step explanation:
The risk of a 22-year-old male developing schizophrenia if his brother has been diagnosed with the disease can be influenced by genetic and environmental factors. Based on the research, the presence of a first-degree relative with schizophrenia significantly increases risk compared to the general population.
Although the precise percentage is not provided in the provided information, it is suggestive that genetics play a role along with environmental factors in the development of schizophrenia. The data indicates that those with a high genetic risk and a disturbed family environment have the highest likelihood of developing the condition.
To calculate the specific risk for the individual in question, additional information is needed such as family history beyond the brother, presence of other risk factors, and environmental background. However, the provided data suggests that the risk is much higher than the general population risk of 1%.
If we only consider genetic predisposition, ignoring environmental factors for simplicity, previous studies have shown that having a sibling with schizophrenia can increase an individual's risk to about 10%. However, since we lack a definitive number from the data provided, we cannot precisely determine the risk percentage for the 22-year-old male.