Some twin studies suggest that heritability is higher among men than women (Cloninger, 1987; Zuckerman, 1999). Zuckerman’s (1999) investigation of concordance rates in male and female twin pairs shows that male monozygotic twins have the highest rates (68–76%), with female monozygotic twins demonstrating significantly lower rates (32–47%). However, results from studies utilizing larger samples of adult male and female twin pairs counter these results. Here, genetic risk factors are equally influential on the development of AUDs in men and women (Heath et al., 1997; Prescott, Aggen, & Kendler, 1999). There is also some work with adult samples suggesting that there are gender differences in the effects of various candidate genes in explaining AUDs (Wodarz et al., 2003). One possible explanation for inconsistent findings in genetic risk across genders is that genetic effects may interact differently with environmental factors such as parenting factors across genders (Miles, Silberg, Pickens, & Eaves, 2005). However, more research is needed to explore this further. Clearly, the impossibility of parsing out the environmental factors in research examining heritability of AUDs in adolescents, as well as the limitations of diagnostic criteria when assessing men versus women (Searles, 1988) suggest findings should be interpreted with caution.
