After three generations of bidirectional selection for ethanol preference, there was a marked difference between the high and low lines (Fig. 1). At S3, the difference in preference ratio was 0.49 vs. 0.15 (F1,209 = 103, P < 0.001). In both groups, females showed a preference than males (F1,209 = 20, P < 0.001). Notably, 65% of females and 37% of males of high preference lines achieved a preference ratio of >0.5 compared with 6.5% of females and 2.3% of males of low preference lines.
