The heritability of drug and alcohol dependence and related phenotypes has been studied in at least 3 Native American populations. In these studies, heritability (h2) estimates were obtained from data collected in large extended families. The earliest study was conducted in the Southwest American Indian population and found that DSM-III-R alcohol dependence was heritable, though exact heritability estimates were not presented [18]. Alcohol dependence in the California Indian population showed some evidence of heritability (DSM-III-R: .19, DSM-IV: .38) [19], and was also found to be associated with degree of Native American Heritage [20]. However, little evidence was found for the heritability of alcohol dependence in the Plains Indian population (David Goldman personal communication, 2008). In contrast, twin studies of alcohol dependence have consistently yielded significant evidence of heritability, ranging from .50-.65 using general population samples with participants of predominantly Caucasian origin [see 21].
