Sperm donors live in and move through what could be called biosocial kinship trouble. On the one hand, they contribute to the conception of new life with their semen samples and are therefore genetically connected to individuals conceived with the help of these samples, connections understood as morally significant by the dominant kinship discourse in Western Europe. On the other hand, they are not viewed as fathers and therefore also positioned as not having any moral responsibilities for donor-conceived individuals by the organizational and legal contexts that regulate their partaking in sperm donation. By definition, sperm donors are thus left to figuring out themselves the complexities of relatedness in a time in which the logics and politics of reproductive biomedicine have become normalcy. In this presentation, we explore how sperm donors negotiate the moral responsibilities of being connected with and relating to people through the use of sperm donation and donor insemination. Based on interviews with sperm donors in Sweden and Denmark, we will look at how donors determine what kinds of moral responsibilities come with being a sperm donor. We will ask how these responsibilities relate to donors’ connections to donor semen recipients, donor-conceived individuals, donors’ own families and loved ones, and, not least, the different biographical, legal, and organizational contexts donors find themselves in. Exploring sperm donors’ moral responsibilities in this way, the presentation thus offers insights into the formation and materialization of relatedness in times of biosociality.