Children given even small quantities of alcohol by their parents drink substantially more than their peers by the time they are 15. However, there is some evidence for the belief that they will be less likely to engage in binge drinking, a first-of-its-kind longitudinal study has found.

There is a long-standing theory that if parents want to stop their children drinking too much it's best to give them small amounts early. The idea, popular in some countries, is that this will make drinking less of a rite of passage, and something more likely to be pursued in moderation.

Surprisingly, given how much concern there is about alcohol over-consumption, no long-term study has focused on the issue prior to this study, published in Psychological Medicine, which looked at the factors influencing drinking in 1,927 Australian adolescents aged 12-15.

Participants in this study whose parents gave them alcohol consumed 5.7 times as much, the paper reports. However, such a finding needs to be treated with great care. As lead author Professor Richard Mattick of the University of New South Wales told IFLScience, “there is a genetic component to alcohol consumption” along with many environmental factors. Heavy drinking parents might be more likely to indulge their children, who were possibly more prone to taking up drinking anyway.

To allow for this, Mattick and his co-authors looked at 28 factors that might influence the propensity to drink and conducted sophisticated regression analysis to try to tease out the influence of each of these on its own. Their conclusion is that adolescents who had been given alcohol by their parents were drinking 1.8 times as much, even when all other factors were allowed for.

“There is a body of research indicating that the adolescent brain is still developing well into the early 20s and alcohol may interfere with optimum development,” Mattick said in a statement. However, many people are more worried about their children getting blind drunk, rather than their total consumption, and on this the results are less clear.

Those adolescents who had been given alcohol by their parents drunk less per session. In raw data the were more likely to consume more than four drinks at a time, but actually did less binge drinking when Mattick controlled for factors such as the parents' own consumption.

The authors have funding to continue to follow the same group until the age of 22. Mattick told IFLScience they see this as important, since other studies on the topic have either been limited in time – looking at drinking rates at only two, or at most three, ages – or have been sidelined to studies looking at many other things, and therefore unable to focus closely on drinking alone.