panels of inbred strains. A recent review of several of those studies was able to compare relative strain preference ratios for 10% ethanol across decades, laboratories, and small variations in the procedures employed. Despite the inevitable genetic drift due to differential new mutations within strains over more than 150 generations, the correlations of strain mean preference ratios exceeded r = 0.90 for any pairwise correlation between data sets. Not only is this a highly heritable trait, it is highly genetically stable over time and laboratories (Wahlsten et al. 2006). As this animal model represents an aspect of the human disease, these results indicate that the genetic contribution to quantity of alcohol intake is profoundly important and supports further consideration of including this index in the scheme used to diagnose human alcohol use disorders.
