Nuremberg, Germany  - Parents who discover their teenager is smoking cannabis should not overreact, but remain cool and collected, a German child guidance specialist advised.

Andreas Engel from Germany's Bundeskonferenz fuer Erziehungsberatung, an association that groups together the country's child guidance councillors, says parents should also inform themselves about marijuana's main active ingredient, THC.

Only then is it a good idea to raise the matter with your child and talk about the effects of smoking the substance. If you are strictly against smoking cannabis, you should make that perfectly clear and ban its use as far as practically possible.

A not inconsiderable portion of teenagers in Germany smoke grass. There are a number of reasons why they turn to the substance.

"Cannabis-smoking teenagers are demonstrating to themselves and their peers that they can break conventions. They're also testing the limits of their independence from the norms of the adult world and showing their affiliation to a youth sub-culture," says Engel.

It is important for parents to point out the health risks, legal consequences and other negative aspects of illegal drug abuse, according to Engel. They should also highlight the positive side to not smoking cannabis.