The current results are not without limitations. First, individuals in the ALSPAC sample were, on average, only around 18 years old when they reported on alcohol-related problems. This is a relatively early stage of one’s drinking “career” and participants are not yet through the risk period for the development of alcohol problems, which stretches well into adulthood. In addition, the age of participants could be related to the rather low estimates of heritability, as previous studies have demonstrated that the heritability of alcohol-related phenotypes typically increases from adolescence into adulthood [9]. These changes are typically thought to be due to greater autonomy in adulthood, enabling individuals’ genetic liability to develop to a greater degree than is possible in the context of the social controls often present during adolescence. It is possible that genetic effects could play a more substantial role in risk for alcohol problems later in participants’ lives, and that alcohol problems may be more pronounced among the unobserved sample.
