Master Card, Visa, Electronic check, American Express, Discover Card
most countries
DrugsMeds
--
--
14-24 days/free
Visa, Electronic check, Wire Transfer
worldwide
Mx-Pharma
--
--
8-16 days/$20 5-9 days/$30 3-6 days/$40
Visa, ACH (Online Check USA)
most countries
WorldRxStore
--
--
15-30 days/$10 7-15 days/$25 3-7 days/$50
Visa, Master Card, JCB, American Express
most countries
ALCOHOLISM AND GENETIC FACTORS: TWIN AND ADOPTION STUDIES
Scientific investigational methods using an experimental model are not possible in the task of separating nature and nurture. Human research requires locating individuals with particular life experiences or characteristics and then comparing them to those with other backgrounds. Twin studies and adoption studies are the two classical methods for doing this. Donald Goodwin is an alcoholism researcher who has worked extensively on the topic of alcoholism and heredity. Many of his (and others') studies have used data from Scandinavia, because these countries keep very complete records of marriages, births, and other data, making it easier to trace families. One early study was based on a large sample of twins. In each set, one twin was alcoholic. The researchers determined whether the twins were identical or fraternal. They then interviewed the twin of the known alcoholic. The prediction: if alcoholism has a hereditary basis, the other twin of identical sets would then be more likely to also be alcoholic than if he were fraternal. The assumption was made because identical twins share the same genetic material. That proved to be the case. However, the hereditary endowment does not act to totally dictate the development of alcoholism because not all the identical twins were both alcoholic. It was further discovered that there exists an apparent predisposition toward having, or being spared, the social deterioration associated with alcoholism. If both twins were alcoholic, the best predictor of the other twin's life situation was not how much or how long he had been drinking. The life situation of the first twin was more reliable. So there appears to be a hereditary predisposition both to alcoholism and the social problems associated with it.
An adoption study conducted by Goodwin using Danish subjects further supports the influence of heredity. He traced children born of alcoholic parents. These children had been adopted by age 6 weeks. He then compared them to adopted children of nonalcoholic biological parents. The adoptive families of both groups were essentially the same. He discovered that those whose natural parents were alcoholic were in adulthood themselves more likely to be alcoholics. Thus the alcoholism cannot be attributed simply to the home environment.
The subjects of the above studies were men. Some initial work has been conducted with female adoptees. The results have been less conclusive, perhaps because the sample sizes were smaller. Also, given the strong cultural prohibitions against women drinking heavily, this may have served as a cultural "protection" against the development of alcoholism.
Further studies based on half-siblings (again males) have helped separate the relative influence of genetic makeup versus home environment. Of the half-siblings, one had an alcoholic parent, the other did not. Thus, one of the children had a biological predisposition the other did not. The children were raised together. In a portion of the cases both were raised in a nonalcoholic family. In other cases, both grew up in an alcoholic home. As expected, those with genetic background positive for alcoholism were themselves more likely to develop alcoholism. Of equal significance, being reared in an alcoholic home did not further increase the likelihood of developing alcoholism for either the biologically at-risk children or those without a biological predisposition. This has been confirmed by other studies; being reared in a home with the alcoholic parent does not further increase the probability of alcoholism. Such findings provide strong support for the importance of the genetic predisposition in some cases of alcoholism.
