Teens who think their parents use cannabis are more likely to hold favourable attitudes toward the drug and to consider trying it themselves, according to a new Washington State University study.

The research, published in the Journal of Child and Family Studies, also reveals that parental monitoring and the closeness of parent-child relationships play crucial roles in adolescents' views about cannabis, often with distinct effects based on the parent's gender.

The findings could ultimately help parents who use cannabis come up with more effective strategies for communicating about the health risks of the drug with their children, especially in states like Washington, where cannabis is legal and mixed societal messages complicate discussions of substance use.

"Parents need to recognise that their use matters," said Stacey J. T. Hust, lead author of the study and a professor of communication at WSU. "If teens perceive their parents use cannabis, whether they do or not, it can send the message that the behaviour is also acceptable for them, especially without explicit conversations that set boundaries for the teen."

For the study, the WSU team surveyed 276 adolescents aged 13–17 in Washington state about their perceptions of parental cannabis use, their closeness to their parents and the level of parental monitoring in their lives. Key findings show that 32% of teens believed their fathers used cannabis, while 25% thought their mothers did. These perceptions were strongly associated with decreased negative attitudes toward cannabis and increased intentions to use it.

Interestingly, the study found that the influence of parental closeness differed by gender. Adolescents close to mothers who were non-users reported lower intentions to use cannabis. Conversely, teens close to cannabis-using mothers exhibited more positive attitudes and stronger intentions to use the substance. For fathers, closeness was associated with more positive attitudes toward cannabis use, regardless of whether the father used cannabis or not.

The researchers also found that parental monitoring can be a powerful protective factor against underage cannabis use, particularly for boys. Boys who reported higher levels of parental monitoring—measured by parents knowing their whereabouts and who their friends were—expressed more negative attitudes toward cannabis than girls under a similar level of supervision.

"Parenting is highly gendered," said Hust. "This study sheds light on how mothers and fathers uniquely impact their children's views on cannabis, providing a roadmap for future research to explore these differences further."

Hust and Jessica Willoughby, an associate professor of Communication at WSU and co-author of the study, said the overall message for parents is that open, honest discussions about cannabis, combined with consistent monitoring, can help mitigate teens' likelihood to view the substance positively or intentions to use it. They recommend parents frame cannabis as an adult decision, akin to alcohol or tobacco, and emphasise its risks.

"Parents need to be thoughtful about how they talk about their use with their kids," Willoughby said. "They need to make clear that cannabis is a product meant for adults and communicate its potential harms, especially for developing adolescent brains."

Moving forward, the researchers plan to build on their study by investigating how parents communicate with their teens about substance use. Future work will explore topics such as the role of parental warmth and closeness in fostering effective conversations about cannabis and other health-related behaviors.