While the heritable nature of alcohol use is well established, there is less information available regarding the continuity of genetic factors between adolescence and adulthood. Generally, genetic influences on alcohol use increase from adolescence into young adulthood before stabilizing (Bergen et al. 2007; Hicks et al. 2007; Kendler et al. 2008b ; Sartor et al. 2008; Edwards et al. 2011a; Geels et al. 2012), though some studies suggest the opposite (Malone et al. 2004; Hicks et al. 2007; van Beek et al. 2012). However, the extant literature largely focuses on total heritability, without exploring whether there are qualitative changes underlying total heritability over time. That is, it remains unclear whether the genetic influences on alcohol use during adolescence are the same as those that are relevant during adulthood. One study, examining symptoms of alcohol-use disorder in a longitudinally assessed sample of Dutch twins, found that while the total heritability of these symptoms varied from the age of 15–17 years to the age of 30–32 years, this variation was only quantitative in nature: a single genetic factor accounted for heritable influences
