This paper considers the ethical, legal, and social issues raised by the prospect of increasing use of psychiatric genetic data in child custody litigation. Although genetic tests cannot currently confirm a parent or child’s psychiatric diagnosis, it is likely that as relevant findings emerge, they will be introduced in family courts to challenge parental capacity. Here, we draw on three projected, but plausible, scenarios for obtaining psychiatric data about parents — imposed genetic testing, access to medical records, and genetic theft — then consider the use of psychiatric genetic data of children, to highlight the issues that judges, child custody evaluators, and clinicians who may provide treatment for parents or children with mental health issues will need to consider. These include: genetic privacy, stigma, genetic surveillance, and judicial and health professionals’ bias. We argue that the unchecked introduction of psychiatric genetic data may have a detrimental effect on the administration of justice. In particular, the article highlights the risk that the (mis)use of psychiatric genetic data in custody disputes would 1) exacerbate stigma and treatment-avoidance among parents and incentivize privacy violations to pressure parents to relinquish parental rights; 2) disproportionately affect poor parents and single mothers of color involved with Child Protective Services; and 3) detract attention from social and environmental factors impacting mental health to the detriment of the families involved. Awareness of these issues and an understanding of the meaning of genomic data by judges and custody evaluators will be pivotal in ensuring that justice is served.