alcoholism families are supported by research using genetic and biological markers in animal models , some of these marker predispose an individual biochemically to increased susceptibility
to developing alcohol-related problems. while other may actually be protective in nature . for example ,genes that code for enzymes that inhibit the normal metabolism of alcohol could cause one to respond positively to the effects of alcohol and thus to drink more, or respond negatively to alcohol and thus drink less or not at all. A study has providence in support of the idea that genes also influence cigarette smoking .the heritability of susceptibility to other drugs is still under investigation.