Adoption study

Adoption studies are one of the classic tools of behavioral genetics. These studies are used to estimate the degree to which a trait varies in response to environmental and genetic variation. Adoption studies are typically used together with twin studies when estimating heritability. There are two adoption study designs. The adoptee's method investigates similarities between the adoptee and their biological and adoptive parents. Similarity with the biological parent is expected to be heritable genetic effect, while similarity with the adoptive parent is associated with home-environment, called the shared environmental effect. The familial method compares non-biological siblings who are reared in the same household. Similarity to non-biological siblings raised in the same household is attributed to shared environment effect, as the siblings are biologically unrelated but share the home environment. Variation that cannot be accounted by either genetics or home-environment is typically described as non-shared environment. Adoption studies are one of the key tools in behavioral genetics and are typically used in combination with twin studies when making habitability estimates.

Although adoption study is a topic that does not have much information discovered, it has been tested and observed that a persons surrounding and genetics effects who they are. In order to study what factors resemble a person's personality, adoption studies is most commonly used for testing. The reason for this is because experimenters are able to see and differentiate between the affect a human has by their biological factors and environmental factors. Another topic to observe is whether certain traits or habits a person expresses are inherited by their biological parents or adoptive parents. Although adoption study is the most effective way of discovering how personalities are created, many times it is difficult to link an adopted child to their biological family or vice versa. In most adoption cases it has been discovered the child will live a comfortable and happy life, but there are those that express a mental or emotional disorder; 14% to be specific.

The first adoption study on schizophrenia in 1968 by Leonard Heston demonstrated that the biological children of schizophrenic parents were just as likely to develop schizophrenia whether they were reared by the parents or adopted and was essential in establishing schizophrenia as genetic instead of being a result of child rearing methods. This discovery was done through a process of interviews of both a child that was adopted along with their biological mother who contained the schizophrenia gene, and of adopted child along with their mother who did not contain the schizophrenia gene. The experiment was conducted more than once on various families and continued resulting on the schizophrenia child inheriting the gene from his mother. This supports the theory that it doesn't matter what specific environment a child is raised in; if its parent or parents suffer from a mental disorder, the risk for suffering from the same disorder will be equal regardless of if the child was raised with its biological parents or with its adoptive parents (Plomin et al., 1997).Similar studies that followed have shown that mental disorders such as alcoholism, antisocial behavior, depression and schizophrenia have a large genetic component that interacts with environmental risk factors such as family conflict, poor cohesion and deviant communication. Recent studies has shown that childhood disorders are not only genetic, but form in more children that are adopted vs children that are not adopted. Many researchers of this topic believed the disorder developed over the time the child was adopted. With further research being done, results have shown that some of the adoptees had been already diagnosed with the disorder before they were even adopted. Researchers concluded the disorders are caused by the way a child is raised and also from the genes of their birth parents. The other few may have developed the disorders after being adopted due to curiosity and trouble finding their true identity. Parents that are willing to adopt are always advised to be aware of the phenomenon that a child that is to be adopted may need help on dealing with psychological issues.

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