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Researchers say a parent’s marijuana use increases the likelihood their child will also use the drug, as well as alcohol. Getty Images
  • A new study concludes that children whose parents use marijuana are more likely to use the drug themselves.
  • Researchers say the study is important because of the rise in marijuana use and its legality in a growing number of states.
  • Experts say a child’s home environment, as well as their parents’ views on social issues such as marijuana use, are contributing factors to this trend.

If you eat cookies, your kids may end up eating them, too.

When it comes to marijuana, the same logic may apply.

According to a new study, recent and past use of marijuana by parents was associated with increased risk of marijuana, tobacco, and alcohol use by the children living under their roof.

The data for the study, published in JAMA Network Open, came from the National Surveys on Drug Use and Health (NSDUH) from 2015 through 2018, which included information from 24,900 parent-child pairs.

The study found that parental past-year marijuana use was consistently associated with a generalized risk of past-year marijuana, tobacco, and alcohol use as well as opioid misuse among both adolescent and young adult offspring living in the same household.

Does this come as a surprise? Not to the experts interviewed by Healthline. But they say that makes the findings no less important.

“Most surprising was that lifetime use of marijuana by parents, even if they did not use in the past year, conferred a higher risk for their children’s substance use,” said Bertha K. Madras, PhD, a professor of psychobiology at Harvard Medical School in Massachusetts, who was corresponding author of the study in the JAMA journal.

“Also intriguing was that mother’s use was more influential than father’s use for youth 12 to 17,” she said.

Madras says there were important reasons to conduct this research, which was jointly sponsored by the Substance Abuse and Mental Health Services Administration and National Institute on Drug Abuse of the National Institutes of Health of the Department of Health and Human Services.

First, parent use of marijuana is rising, she said, “and I wondered whether this could be associated with offspring use of specific substances and across several substances.”

Also, on a personal level, Madras said, “several fathers have confided in me that they used marijuana to bond with their sons. They became horrified after witnessing their sons progress to using other drugs, especially heroin.”

Madras explains that few studies have directly examined whether parental marijuana use elevates the risk of opioid misuse among adolescent and young adults living at home with parents.

“Most importantly, and to the best of our knowledge, none of the existing research simultaneously explored frequency of parental marijuana use and whether it related to adolescent and young adult offspring’s marijuana, tobacco, alcohol use, and opioid misuse,” she noted.

While there may be no audible gasps about the findings, Madras believes this is vital information for all parents.

“The study [will] inform clinicians and policymakers that screening for marijuana use and educating individuals, patients, and families about the risks is essential,” she told Healthline.

Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML), was also not surprised by the research. But he points to the study’s theory that environment is likely playing a role here, as opposed to some sort of genetic or familial link.

“Homes where the parents hold more liberal attitudes toward substance use, or where the parents use certain substances themselves, likely foster a more permissive environment toward substance use than do homes where substance use is strictly forbidden,” Armentano told Healthline.

“It is also plausible that children have easier access to these substances in homes where parents engage in their use as compared to homes where drugs and alcohol are not present,” he said.

Armentano believes that ideally parents should be aware of how their behaviors may influence their children’s attitudes and behaviors.

“They ought to engage in thoughtful, evidence-based discussions with their children surrounding use versus abuse, when such behaviors are age appropriate, as well as the reality that the use of marijuana or alcohol by those under the age of 21 is illegal and may result in serious legal consequences,” he added.

Linda Richter, PhD, director of policy research and analysis at the Center on Addiction, says this study underscores the fact that the most essential place to focus efforts to curb youth substance use is the home.

“Research like this consistently demonstrates that parents are the most important influence on their children when it comes to substance use. And the stakes are very high,” she said.

“People who begin using marijuana, tobacco, alcohol, or other drugs in adolescence are at far higher risk of developing addiction than are those who wait until they are adults. Our own research found that, in the case of marijuana, the odds of addiction among youth versus adults who use the drug is about twice as high,” Richter said.

This is a case where actions speak far louder than words, she adds.

“Conveying through their actions that using an addictive substance to relax, have fun, get energized, or assuage bad feelings is normal or routine carries great weight with impressionable teens and young adults,” Richter explained.

“As marijuana in particular becomes more accessible and normalized in the liberalizing regulatory climate, resources should be directed at efforts to make parents aware of the strong intergenerational influence of their substance use decisions and behaviors,” she said.

Kenneth Leonard, PhD, director of the Clinical and Research Institute on Addictions at the University at Buffalo in New York, says the findings are consistent with extensive research literature that shows that patterns of parental alcohol and drug use are associated with the alcohol and drug use of their adolescent and young adult children.

However, he notes there are still other factors to consider.

“Substance use in adolescence and young adulthood is the consequence of a number of sociocultural, peer, and parental factors, including genetic factors,” he explained, “that operate throughout childhood, impacting each other and creating a developmental cascade that leads to substance use.”