To explore these issues, the current study used linkage analyses of heaviness of alcohol consumption. The samples examined were ascertained for multiple purposes and included data from some individuals who were assessed on two occasions, approximately 8 years apart on average. Thus, we are able to compare linkage results for somewhat younger versus older samples. Will the trend for heavier drinking among younger participants enhance linkage in the sample maximising data collected at the younger age? Or conversely, will stronger environmental influences on consumption in younger individuals, as suggested by the lower heritabilities found in our younger cohort (Hansell et al., 2008), dampen linkage signals?
