"Alcohol still remains the most dominant substance of abuse in South Africa," said the social development department.
"Children who are drinking alcohol by 7th grade are more likely to report academic problems, delinquent behaviour in both middle school and high school," said the social development department.
It said research by the Central Drug Authority indicated that a third of grade 11 girls consumed alcohol while just under half of boys in the same grade did.
By young adulthood, those who began drinking early could experience employment problems, abuses of other substances and violent or criminal behaviour.
Central Drug Authority deputy chair David Bayever said: "We cannot just blame the abuse of drugs on a genetic predisposition as genes have not changed over the past few years".
Any parents, young people or communities who needed assistance with substance abuse should call the department's alcohol and drug abuse line at 0800121314 or send an SMS to 32312.
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