Preimplantation genetic diagnosis (PGD) has been used not only to avoid genetic diseases and increase conception success rates but also to perform non-medical sex selection, particularly in the surging cross-border reproductive care (CBRC). In the context of commercialised biomedicine, assisted reproductive technologies, such as lifestyle sex selection, have been tailored to meet intended parents' preferences. However, there is a lack of analysis on how individuals' reproductive decisions on PGD-assisted sex selection were shaped within the sociocultural norms and CBRC. This article explores Taiwanese gay fathers' navigations on sex selection while seeking third-party reproduction overseas because of local legal constraints. Drawing on in-depth interviews with 53 gay fathers (to-be), I analysed how 'individual preferences' were dynamically shaped by local sociocultural norms and embedded within transnational settings of routinising PGD in chosen repro-destinations. The findings showed that gay fathers mobilised strategic discourses on non-medical sex selection from both the local and the global to negotiate their decisions in coherence with their LGBTQ+ identity and their role as sons carrying familial responsibility to procreate male heirs. This article proposed a nuanced understanding of gay fathers' reproductive practices of 'gendering the beginning of life' through PGD-assisted sex selection.