Another group of studies are known by the shorthand title of "genetic marker" studies. In such investigations, attempts are made to link alcoholism to any traits that are known to be inherited. This would establish a genetic basis for alcoholism. Some of the possibilities that have been studied include blood types. It is known that blood type is inherited; the genes controlling this may also be responsible for other characteristics. Other leads that have been followed include other blood substances; ability to taste or not taste phenylthiocarbamide; and blue-yellow color blindness. While no one link has yet turned up, research is proceeding at a rapid pace on several promising fronts.

Familial alcoholism

Given the strong evidence for the role of a genetic factor in some cases of alcoholism, researchers are suggesting that we begin to think in terms of two types of alcoholism, familial and nonfamilial. Goodwin suggests that familial alcoholism is characterized by a positive family history of alcoholism, earlier age of onset, more "destructive" symptoms that necessitate treatment at a relatively young age, and no increased likelihood of other psychiatric illness.

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