Philosophical theories about parental licensing tend to pay insufficient attention to forms of discrimination that may be inherent in, or result from, a system of parental licensing. By situating these theories in relation to the status quo on parental licensing, we aim to show how many of them reinforce what philosophers have called “biologism”: the privileging of families formed through biological reproduction over families formed in other ways. Much of our discussion focuses on biologism, although we also touch on other forms of discrimination that parental licensing can cause or exacerbate, such as classism, sexism, homophobia, racism, and ableism. We firmly believe that any adequate proposal in favour of parental licensing must take worries about discrimination seriously. Unfortunately, most philosophical proposals fail to do so.