The potential of social media to create open, collaborative and participatory spaces allows young women to engage and empower themselves in political and social activism. In this context, the objective of this research is to analyze the polarization in the debate at the intersection between the defense of feminism and transsexuality, preferably among the young public, symbolized in the use of the term “TERF”. To do this, the existing communities on Twitter and TikTok on this subject have been analyzed with Social Network Analysis techniques, and the presence of young people in them. The results indicate that the debates between both networks are not very cohesive, with a highly modularized structure that suggests isolation of each community in itself. For this reason, it can be considered that the debate on sexual identity has resulted in a strong polarization of feminist activism in social media. Likewise, the positions of transinclusive feminism are very majority among young people, which reinforces the idea of an ideological debate that can also be understood in a generational perspective. Finally, a differential use between both social networks has been identified, where TikTok is a less partisan and more dialogical network than Twitter, which leads to discussions and participation in a more neutral tone.