... In the present study, this issue applied more to girls than to boys, so that in addition to the " Family history of drug use " risk factor, other family risk factors such as " Poor family management " , and " Parental attitude favorable toward drug use " with high OR as well as " Family conflict " were the predictors of lifetime tobacco product use only in girls, but not in boys. It is argued that girls are probably more sensitive to family issues, or since they spend more time indoors compared to boys, they interact more with parents and are more exposed to family conflicts (Fagan et al., 2007), As resarchers have shown that the most effective factor in family interactions is length of time spent with the family (Adlaf & Ivis, 1997). However our study is in agreement with studies that found family factors stronger predictors in girls than boys (Farrington & Painter, 2004; Blitstein, Murray, & Lytle, 2005; Yeh, Chiang, & Huang, 2006; Choquet et al., 2008; Sanchez, Opaleye, & Martins, 2010;), Other studies have found the above factors more dominant in boys (Moffitt, Caspi, & Rutter, 2001; Piquero & Sealock, 2004) or have not found a significant difference between boys and girls in terms of existing risk factors in the family (Loeber, & Stouthamer-Loeber, 1986; Rowe, Flannery, & Flannery, 1995; Fergusson & Horwood, 2002). ...