Dual alcohol and cannabis use in male and female adolescents: Relationships with family variables

•Family variables influence the probability of being an alcohol and cannabis user with sex differences.•In boys, family conflict was associated with a greater likelihood of being alcohol-user and dual-user than non-user.•In girls, higher scores in family communication were associated with a lower probability of consuming alcohol.•Girls who reported greater consequences for breaking the rules were associated with a lower likelihood of being dual users than non-users or only alcohol users.•Not just family involvement that is needed in prevention and intervention for substance use in adolescence, gender differences also need to be considered. Family dynamics influence adolescents’ use of alcohol and other substances, such as cannabis. The aim of this study was to understand the relationship between family variables and alcohol use, dual use of alcohol and cannabis, and non-use in adolescents according to sex. A cross-sectional study was conducted. The sample comprised 879 adolescents (56.4 % boys; M(SD)age = 14.25 (1.88) years). Multinomial regression analysis showed that for boys, the presence of family conflict increased the likelihood of being an alcohol (OR = 1.19) and dual (OR = 1.23) user rather than a non-user. For girls, communication reduced the probability of being an alcohol user (OR = 0.88), and the presence of consequences for breaking rules reduced the probability of being a dual user rather than a non-user (OR = 0.83) or an alcohol user (OR = 0.84). These findings highlight the importance of family prevention of adolescents’ substance use, bearing in mind the participants’ sex.