Although many gene mapping studies are carried out in Ashkenazi Jewish (AJ) samples (i.e., all four grandparents born in Europe; (Guha et al., 2012), due to the unique genetic structure of that population (Guha et al., 2012), we decided to also include non-Ashkenazi Jews (NAJ; mainly of Middle Eastern origin), to determine if the same genetic effects were found in both potential subpopulations (AJ/NAJ). The AJ/NAJ distinction also connotes cultural differences, possibly encompassing differences in drinking behavior. Although we asked respondents to self-identify as “Ashkenaz” or “non-Ashkenaz”, close to 20% of the sample chose “both” or “other”, reflecting the blurred distinctions between these categories, both in terms of cultural practices and genetic origins (i.e. individuals with grandparents from both groups), in modern-day Israel. Therefore the traditional AJ/NAJ distinction was not useful in this sample. Rather, we used AIMs, which produced a continuum of genetic ancestry measuring the Northern/Southern European cline, with higher proportion of “Northern” ancestry indicating more Ashkenazi origin, and higher proportion “Southern” ancestry indicating more non-Ashkenazi origin (Listman et al., 2010). We analyzed the whole sample (instead of
