male twins (i.e., 7.9 versus 5.3), although again the difference was not significant. For women, Koskenvuo and colleagues (1984) found no same-sex twin pairs in which both twins had an alcoholism discharge code, making it impossible to estimate a risk ratio. Allgulander and colleagues (1991, 1992) found substantial risk ratios for MZ and DZ female twins of female alcoholics (i.e., 41.9 and 16.5, respectively), but again these do not differ significantly.
