Summarize research findings on the role of genetics and environment in the development of psychological disorders.

There are a number of research studies focusing on behavior genetics and showed that most of the personality traits are related to both biological and environmental bases. An example of one such trait is Intelligence. The most common research methodology adopted to find out the behavior trait of the person could be categorized based on the genetic and environment. In genetic part, the research is focused on family genetic studies, twin and adoption studies, while in environmental part could be divided into two shared (shared by siblings) and non-shared environment (environment unique to the individual). The studies have shown that no single genes are responsible for the personality trait, or intelligence or behavior of the person it is a complex characteristic, which is influenced by both genetics (hereditary) and the environmental. In family studies, have showed that children share 50% of the genes, while twin shares 100% of their genes and while dizygotic siblings share 50% of their genes. Finally, results show that both genes and environmental both are very important, as they act together (synergistically) while shared environment is not so important.