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Study: Parents’ substance use influence their children, but good parenting can break the cycle
The way parents engage with their children matters a great deal.
Adolescents who grow up in a home where parents drink or use drugs increases the likelihood that they will do the same. This is shown in a new study.
When parents drink alcohol, the probability of their child also drinking is 24 per cent higher than if the parents don't drink.
When parents use multiple substances, the probability of their child doing the same rises to 28 per cent.
“This is not destiny, but a risk gradient. And what we found is that the way parents raise their children can significantly disrupt that transmission,” says Professor Dr. Zila Sanchez.
She is head of the Department of Preventive Medicine at the Federal University of São Paulo in Brazil.
The strongest finding: abstinence has the greatest influence
The study is part of the larger research project PREV.ACTION, a community-based randomised trial conducted across four municipalities in São Paulo.
Perhaps the most striking finding in the study was:
When parents themselves use no substances – neither alcohol, tobacco, nor cannabis – 89 per cent of their children are also substance-free.
“It tells us that what parents do matters at least as much as what they say,” Sanchez says.
More than half of the adolescents in the study had never used any substance at all, even though many of them had parents who used substances.
This suggests that protective factors work for many young people and that these factors can be deliberately strengthened.
One parenting style stands out clearly
The study draws on four parenting styles. These are defined along two dimensions: how much warmth and emotional connection parents show, and how much monitoring and structure they provide.
The authoritative style stands out as by far the most protective. These are parents who are engaged and affectionate, while also setting and maintaining clear expectations.
“In everyday life, it looks like a parent who knows where their child is after school, who they spend time with, what they are worried about. At the same time, it's a parent who sets and enforces clear rules about curfews and alcohol, without being punitive. It's the combination of ‘I care about you’ and ‘I have expectations for you’ that seems to matter,” Sanchez explains.
The authoritarian style – high control, low warmth – showed some protective effect against drug use, but not against alcohol use.
One interpretation is that strict control without an emotional foundation may suppress certain behaviours while creating a tension that, in the case of alcohol specifically, opens another door.
Alcohol is more normalised in Brazilian culture than other drugs, and its social pathways are harder to block through control alone.
What can parents actually do?
Sanchez points to three things that stand out clearly from the research:
Maintain a close and open relationship with your child; be someone they can talk to.
Set clear and consistent rules about substance use, including alcohol.
Stay involved in their daily lives; know their friends and be familiar with their routines.
"Knowing where your child is and who they are with has consistent evidence behind it and does not require major changes. A simple daily check-in, genuine curiosity about their friendships, these habits, maintained consistently, are associated with real protective effects," she says.
She also warns against treating alcohol at home as something trivial or inevitable.
“Even parents who otherwise have a good relationship with their children showed a residual association between their own drinking and their children’s. Normalising alcohol at home, regular use at meals, always having it available, is a risk factor regardless of parenting quality,” she says.
Prevention needs to start early
The study suggests that the prevention window – the period during which there is the greatest opportunity to prevent a problem before it develops – is earlier than many parents expect.
In Brazil, where more than half of the population tried alcohol for the first time before the age of 18, initiation is already underway in a significant proportion of adolescents by the age of 14 or 15.
“The preventive foundation needs to be built before that. Parenting styles are not things you switch on at age 13. They reflect patterns established over years,” Sanchez says.
Relevance beyond Brazil
The study was conducted in Brazil, but Sanchez believes the underlying mechanisms are likely to apply more broadly.
She explains that studies from many countries show the same thing: Parents influence their children’s choices through their own behaviour, the way they raise their children, and how closely they monitor them.
Although drinking habits and culture vary from country to country, good parenting appears to protect adolescents from substance use regardless of where they live.
Reference:
Sanchez et al. Does the apple fall far from the tree? When parenting styles disrupt the intergenerational pattern of substance use, Addictive Behaviors, 2026. DOI: 10.1016/j.addbeh.2025.108567
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