<p>Research shows that parental support is crucial for trans and nonbinary youth (TNB) and is associated with reduced psychosocial risks, improved mental health outcomes, increased well-being, life satisfaction, and resilience. Some studies observe that a lack of parental support can contribute to transition interruption (or detransition). However, little is known about how parental support interacts with the experiences of youth who detransition. This article examines how parental support and attitudes are perceived by youth who have detransitioned, with particular attention to the type of support received from pre-transition to detransition. Between 2020 and 2022 we conducted 25 semi-structured interviews with youth aged 16 to 25 who had started a medical or social transition and discontinued it, coming from the US, Canada, Europe, and Indonesia. 20 were assigned female at birth; 5 were assigned male at birth. We conducted a thematic analysis and a retrospective longitudinal analysis. We have observed four distinct support trajectories: the stable trajectory of non-support, the stable trajectory of support, the progressive support trajectory, and the unstable trajectory of support. Only stable (very rare in our sample), and progressive trajectories of support seem beneficial. Others may foster doubts, low self-esteem, imposed gender or sexuality, secret transitions, or precarity. Parental support can impact detrans youth trajectories of transition and detransition; therefore, interventions should help parents better support their gender-nonconforming children. Further research is needed to determine if lack of parental support can be a contributing factor to detransition.</p>