In pediatric oncology, genetic and genomic tests are proposed throughout the care pathway for many reasons (e.g., cancer characterization, identification of the most appropriate treatment, patient selection for clinical trials, identification of tissue/organ donors, or risk of relapse prediction). Despite the many different approaches (somatic or germline testing, targeted gene or genome sequencing), the implicated individuals are confronted with situations that may intersect and that are interesting to compare. No study has identified and analyzed the available works on these new practices in pediatric oncology. The aim of this narrative literature review was to describe the ethical and psychological perspectives of children with cancer, parents, and healthcare professionals when genetic or genomic testing is proposed as part of the cancer management. Eighteen articles met the inclusion criteria and were comprehensively coded using MAXQDA. Their analysis showed that concerning the subjective implications of genetic and genomic testing, the areas of ambivalence (desire of treatment, desire for knowledge, uncertainty, and guilt) reported by patients and their parents seem to mirror the healthcare professionals' concerns. The ethical and psychological issues about predisposition testing, long discussed in the context of hereditary retinoblastoma and Li-Fraumeni syndrome, represent a useful starting point for a wider discussion of a genetic and genomic testing pathway in pediatric oncology more broadly.