Existing evidence indicates higher psychological distress and risky sexual behaviour among sexual minorities; however, the evidence is mostly cross-sectional. The Mendelian Randomisation-Direction of Causation (MRDoC) model can determine the direction of causal effects in these relationships and estimate the magnitude of these effects while adjusting for residual genetic confounding. Considering that childhood factors such as childhood gender nonconformity and early life adversities are higher among sexual minorities and each associated with adverse health outcomes; it is possible that both factors moderate these causal relationships. Only one study has previously demonstrated significant causal influences of same-sex attraction on both adverse health indices, and reverse causal influences flowing towards same-sex attraction (Oginni et al., under review). These findings were respectively consistent with the minority stress theory and feedback effects of adverse health outcomes. However, this study did not test the possibility of sex differences in these relationships or moderation of these relationships by childhood factors.