Genetic influences
Genetic studies have provided valuable information about inheritance of susceptibility to disease (Harmone, 2004). in human several types of research help demonstrate whether a characteristic is genetically required or not. if a factor is genetically determined family members are expected to show it more frequently than unrelated individuals. Twin studies is a method of examining genetic basis of characteristics, whether a character genetically transmitted, identical twins share a disorder more frequently than fraternal twins since they have exactly the same genetic makeup. adoption studies helps in segregating genetic characteristics of environmental ones. Adoption studies and two in studies together have uncovered the role of genes and their behaviour in psychiatric disorder both in psychotic and neurotic ones. Chromosomal abnormalities where there is sometimes addition deletion translocation or mutation of genes result in psychiatric and genetic disorders like Down's syndrome, Klinefelter's syndrome etc which clearly arises from the genetic basis.