Out of a sample of 1,614 individuals, the maximum number of drinks was recorded for 1,388 (86%) individuals. The mean, median, and mode were 17.8, 12, and 24, respectively, with a standard deviation of 17.3. Due to computer memory constraints, 9 out of 143 families (6%), consisting of 243/1,614 (15%) individuals, were automatically dropped by MERLIN from the linkage analysis in stage 1, and this reduction in sample is a limitation of our analyses. The average maximum drinks value in the dropped families was slightly lower than the overall average (by 0.16 of a standard deviation); this difference does not appear to have a systematic cause and is not expected to affect the interpretability of the results.
