Many children have their first taste of alcohol at home
Parents who introduce their children to alcohol in the hope of encouraging responsible drinking might be doing more harm than good, work suggests.
The National Institute of Alcohol Abuse and Alcoholism found drinking before the age of 15 increased a child's risk of becoming a heavy drinker.
A teenager's fast-developing brain becomes programmed to link alcohol with pleasure, experts believe.
Research shows that by the age of seven most children will have tasted alcohol.
A poll of 11 to 15-year-olds in England in 2007 by the NHS Information Centre found around 640,000 were likely to have drunk alcohol in the past seven days.
Of hospital admissions in 2006/7 specifically due to an alcohol-related diagnosis, almost one in 10 were in under 18 year olds.
The NIAAA study matched information on the teenage drinking habits of more than 22,000 Americans with the development of alcohol-related problems.
The men and women were divided into three groups - those who first drank under the age of 15, between 15 and 17, and 18 or older.
People who started drinking before the age 15, and to a lesser extent those who started drinking at ages 15 to 17, were more likely to become dependent on alcohol as adults than people who waited until 18 or older to start drinking.
This link remained even when they took into account factors like duration of alcohol exposure, family history and a wide range of other risk factors.
Research also shows the likelihood of developing alcohol-use disorders in adulthood is about 50% higher for people who start drinking before the age of 15 as for those who abstain until they are 18 or older.
Deborah Dawson, research scientist at the NIAAA, said: "We can see for the first time the association between an early 'age of first drink' and an increased risk of alcohol use disorders that persists into adulthood."
Howard Moss, the institute's director for clinical research, said: "Early alcohol consumption, as a misguided choice, is driving the relationship between early drinking and the risk for development of later alcohol problems.
"The data support the notion of delaying the onset of drinking behaviour as late as possible."
Don Shenker, chief executive of Alcohol Concern, said: "Parents are certainly the best placed group to encourage responsible drinking attitudes among young people, but this study, like others should give them pause about precisely when it's right to start giving alcohol regularly to their children.
"Younger adolescents whose physical and mental development is ongoing ought not to be drinking regularly as successive pieces of work has shown a close connection between that and damage to key systems."
Sarah-Jayne Blakemore of University College London's Institute of Cognitive Neuroscience said young brains were very malleable and changed fast in response to new influences.
Early alcohol exposure could be acting as an environmental trigger for adolescents with an underlying disposition to alcohol problems, she said.
"Although a lot might depend on the amounts drunk as well as the exposure itself," she added.
A spokeswoman from the social care organisation Turning Point said: "At the moment there is simply not enough help for children and families affected by alcohol misuse.
"Without important interventions at vital stages of these young lives, they are much more likely to go on to have alcohol problems themselves."
The NIAAA study will be published in the December issue of Alcoholism: Clinical & Experimental Research.