The Power of Genetic Inheritance

The human behavior has always been one of the fascinating subjects in psychology. However, the mystery of what factor in life is it that makes us behave the way we do remains unanswered. Psychologists all over the world have spent years on determining the behavioral influences and until now, genetic inheritance and nurture are by far the most reasonable explanations when it comes to human behavior. There have been arguments about whether or not genetic inheritance influences an individual’s personality along with numerous studies to support the idea, including the study of Leonard L. Heston and J. M. Baily & R. C. Pillard, which are two famous examples when it comes to genetic inheritance.

The study run by Heston in 1966 was an adoption study. An adoption study is when a child is separated from his/her biological parents, and the similarities in behavior that are later observed in the child are considered as genetic inheritance from the biological parents. The aim of this study was to know if schizophrenia is genetic or not. The researcher would simply do schizophrenia diagnose on foster children and then compare the results with their biological mothers diagnosis. If schizophrenia were to be genetic, then there would be a higher chance for the foster kids whom had biological mothers with diagnosed schizophrenia to have the component as well. The results came as expected, when over 10 percent of the adopted children whom had a family with a history of schizophrenia were diagnosed to have schizophrenia. This was a correlational study with no cause and effect, so there would be no independent and dependent variable. There cannot be an age bias since once diagnosed with schizophrenia, it is unlikely that the results from a diagnosis changes even after years. There were no details to determine whether there was gender or ethnicity bias. Also the test was completely ethical since no harm was done, only a diagnose was taken. A study like this need to be paid serious attention due to the strong evidence it contains. Maybe it may not occur that 100 percent of the time a mother with schizophrenia gives birth to a child with the same illness, but the fact that those children that had schizophrenia had diagnosed mothers as well is sign of great genetic influence. Often we hear that mental issues are something caused by our environment but this evidence claims otherwise. This type of illness is something that an individual is born with, and when born with such an illness, the chances of having symptoms of the illness are far greater than nurturing against them. As long as genetically caused diseases and disorders exist in the DNA, there is almost no chance of ignoring its behavioral influences as it develops with time.

Though there are situations where time does not develop a genetic inherited influence; instead, it is developed under the right circumstances because of the potential that exists. In 1991, Bailey and Pillard performed a study on monozygotic (MZ) and dizygotic (DZ) twins. The aim of the study was to see how often is it that when a twin is homosexual, the other twin is homosexual as well. This was also a correlational study and that’s because the method was to question the participants and their families to obtain and compare their information with one another. The results showed that the DZ twins had a concordance rate of 22% in homosexuality while the MZ twins had about double that percentage, 52%. This is the matter of nurture plays its role in the influence of genetic heredity. The reason why the MZ twins did not get a 100% concordance rate is because environment and nurture affects the amount of influence that a genetic inheritance can have. Even so, the MZ twins got double the rate of the DZ twins and that is proof enough that the same behavioral pattern is witnessed more in those who share a common DNA. Nonetheless, it was a study only done on men so the evidence cannot claim to apply to women as well and that gives an age bias. No mention of age or ethnicity bias but the fact that the MZ twins did not get a 100% due to nurture might be sign of the twins growing in different families or cultures which may have caused only a 52% concordance which strikes out the ethnicity bias. Though the method of acquiring the study data might have been slightly unethical considering that the researchers questioned family members about things that might have been private to the participants.

In the end, the struggle to find the extent of genetic inheritance influence still remains because of the effects of nurture that we receive throughout our lives. More difficult than that is figuring when the behavior is influenced by genetics or nurture considering all studies with the different results that have been obtained over the history of psychology. However, I believe that a logical answer to the extent of this influence would be that the genetic inheritance’s potential exists in our DNA and will develop given the right nurture and circumstances in order to influence the human behavior.