Genetic tests are an efficient and effective diagnostic tool in paediatric neurology, and are increasingly incorporated into the diagnostic work-up of our patients. Significant advances in genetic technologies in recent years has expanded both the scale at which genetic testing can be done, and the speed with which results can be returned. However, there is no “perfect” genetic test which will identify all clinically relevant genetic variants. Understanding the appropriate application of each test type is therefore key to securing a diagnosis. It is vital that consent to genetic testing is freely given and adequately informed. In this article, using clinical vignettes, we will discuss the strengths and limitations of each genetic test, and give an overview of how to take informed consent. Our ability to identify variants has outstripped our ability to interpret them reliably so caution should be exercised. We describe the challenges of variant interpretation, and the importance of Clinical Genetics expertise in this process.