Predictive genetic testing in young people for severe, adult-onset conditions is advised against in current guidelines. Despite this, there has been considerable debate regarding the issue. Some perceive such testing as too potentially harmful to allow. Others perceive it as an opportunity for the promotion of benefit, an opportunity even for the prevention of harm. The only way to resolve this theoretical debate is to collect empirical data related to the effects of such testing when it occurs. However, more than 15 years after the debate began, there is virtually no such empirical evidence available. The reasons for this lack of evidence appear to relate to the rarity of such testing, which when it occurs is not studied systematically. Additionally, clinicians performing such tests may feel vulnerable in sharing the outcomes, given that such testing is contrary to current recommendations. We propose a way forward that entails the provision of tests to mature minors, where clinicians deem this appropriate. These tests should be performed as part of an international research collaboration, facilitated by one leading group.