Parents in families with a hereditary cancer syndrome are often familiar with periodical clinical testing of both themselves and their children. Genetic testing is an additional early diagnostic option that is becoming available for an increasing number of hereditary cancer syndromes. Participants in genetic counseling programs for cancer syndromes are often parents who apply for their children. If a child is identified as a carrier of a specific disease-causing gene mutation, sometimes its parents must decide on when it will be treated can treatment be postponed until expression of the disease or should the child receive presymptomatic surgery? We discuss some of the possible risks of genetically testing children: distress as a result of ambivalent feelings towards testing, preoccupation with disease-related signs, changes in family interactions, the burdening prospect of a future disease and medicalization of the carrier-child.