How parents drink and parent both shape whether teenagers use substances

When parents drink, their children are more likely to drink. That association is not new. What a large Brazilian study adds is a more precise picture of how much parenting behavior can modify that inherited risk - and under what conditions it cannot.

Researchers analyzed data from 4,280 adolescents and their guardians, sorting the young people into three consumption profiles: abstainers, those who drink alcohol only, and those who use two or more substances. They then examined both parental substance use patterns and parenting style, categorizing guardians into four types: authoritative (combining acceptance with monitoring), authoritarian (strict without warmth), permissive, and neglectful.

The findings, published in Addictive Behaviors, arrived in two parts. First, parental substance use matters - substantially. Alcohol use by parents was associated with a 24% probability of their children also consuming alcohol, and a 6% probability of multi-substance use. When guardians used multiple substances, those probabilities jumped to 17% and 28%, respectively.

How parenting style changes the math

The second finding complicates the first. Parenting style - not just what parents consume - significantly shapes adolescent risk. Authoritative parenting, which the researchers describe as combining acceptance with consistent monitoring, produced the most protective effects. Even in households where parents used substances, adolescents raised in this style showed substantially reduced odds of following the same path.

Authoritarian parenting also reduced drug use risk, though its effect on alcohol was weaker. The permissive and neglectful styles offered no protective effects.

"With this study, we reinforce the fact that parents' patterns of alcohol and other drug use influence their children's. However, if they set rules and limits at home and show affection, these protective factors greatly minimize the risk they themselves pose when they consume these substances," said Zila Sanchez, a professor in the Department of Preventive Medicine at the Sao Paulo School of Medicine of the Federal University of Sao Paulo (UNIFESP) and the study's lead author.

The clearest finding: abstinence is the strongest shield

Despite the mitigating effects of parenting style, the single strongest predictor in the study was parental abstinence itself. When guardians did not use alcohol or other substances, 89% of their adolescent children also abstained. That is the highest protective association the researchers observed - stronger than any parenting behavior measured.

"The greatest predictor of abstinence among young people is non-use by their guardians. When they're abstinent, 89% of adolescents also don't use alcohol or other legal or illegal drugs. This was the strongest association we found," Sanchez said.

The finding carries a caveat worth noting. Frequency of parental consumption interacts with the protective value of parenting behavior. When parents consume substances frequently and treat it as unremarkable, even the warmth and monitoring of authoritative parenting provides less protection. "When consumption is frequent and treated as something trivial, it translates into greater risk, regardless of the existing emotional bond," Sanchez explained.

Context: Brazil's adolescent substance landscape

The numbers from Brazil's National Survey on Alcohol and Drugs (LENAD III), conducted by UNIFESP and released in 2025, provide context for the stakes. Despite a legal prohibition on alcohol sales to those under 18, more than half of Brazil's population (56%) tried alcohol before that age, and 25.5% began regular drinking during adolescence.

Among adolescents aged 14 to 17, roughly 27.6% have consumed alcohol at some point - approximately 3.2 million individuals. About 19% reported use in the past year, equivalent to 2.2 million young people. Approximately 1 million adolescents have tried marijuana, with half of them using it in the past year.

Alcohol is a major contributor to chronic noncommunicable diseases globally, including cardiovascular disease, cancer, and diabetes. Delaying the onset of use among young people is considered one of the most effective long-term strategies for reducing future harm - a point that gives findings about parental behavior additional policy relevance.

Limits of the study

The research relies on self-reported data from adolescents and their guardians, which carries known limitations - social desirability bias can lead to underreporting of substance use on both sides. The study is also cross-sectional, capturing a moment in time rather than tracking families over years, which makes it impossible to establish causal direction with certainty. It is also worth noting that the sample is drawn from Brazil, and the specific proportions may not transfer directly to other cultural contexts where alcohol norms, family structures, and parenting practices differ.

What the study contributes is a large, well-characterized dataset showing that intergenerational transmission of substance use is not fixed. Parenting style modifies it. Abstinence eliminates most of it. Both findings have practical implications for family-level prevention programs.