182 Chapter 10 INTRODUCTION This thesis describes the ethical dilemmas surrounding the use of early medical treatment for transgender minors, one specific being competence to give informed consent. The various studies in this thesis cover almost a decade, a time in which significant changes have occurred regarding how transgender minors are perceived, and regarding the care that is provided to them. In 2013, at the start of the first study included in this thesis, the possibility of treatment with puberty suppression (PS) had generated a relatively new dimension to the clinical management of transgender adolescents. It has been an approach of which ethical challenges have been acknowledged since the introduction of it (e.g. Cohen-Kettenis et al., 2008; Kreukels & Cohen-Kettenis, 2011). Even though the use of PS in the care of adolescents was adopted by a rapidly increasing number of gender identity clinics, and the World Professional Association for Transgender Health (WPATH) and the Endocrine Society included this treatment option in their guidelines on care for transgender children and adolescents, many clinicians working with transgender minors remained critical (e.g. Coleman et al., 2012; Coleman et al., 2022; Hembree et al., 2017; Rew et al., 2021; Vrouenraets et al.,2015). Since the introduction of PS, the debate has never been quiet and moved between extremes, and the discussions were at times emotionladen. At that time, it was not fully clear what the underlying thoughts and considerations were of the people who criticize PS treatment, and of those who support the use of PS. In particular, advocates of PS, openly stated their considerations, ideas, and clinical research data regarding PS in, among others, scientific journals (e.g. Hembree, 2011; Olson et al., 2011), while people who criticized the treatment mostly stated their considerations and ideas via social media, and barely in scientific journals (e.g. An interview with Dr. Joseph Nicolosi Part 1/3, 2010; Chemical castration - not the best for children, 2011). Over time, the people who criticize the treatment, and the ones who support the use of early medical treatment do not seem to have come closer to each other; in fact, the debate seems to have become only harsher (e.g. Lament, 2014; Osserman & Wallerstein, 2022). Currently there hardly seems to be little room for a ‘nuanced middle-ground’ anymore (e.g. Bazelon, 2022). In the last decade, people criticizing early medical treatment for transgender minors have also increasingly began to publish their research data and outlining their critical views in internationally peer-reviewed journals, just as providers supporting early medical treatment already did. They state that PS in transgender adolescents should occur in the context of research since the treatment is, according to them, largely experimental (Biggs, 2019; Heneghan & Jefferson, 2019). They stress that there are still too many unanswered questions regarding the treatment; questions that include the treatment’s reversibility, the age at start, its psychosocial effect and impact, the role of physiological puberty in developing gender identity, medical decision-making competence (MDC), transition regret