Differences in DNA methylation between sexes on the autosomes have previously been found and hypothesised to be contribute to the sexual discordance observed in various traits and diseases. Specifically, an analysis in the ALSPAC cohort determined that over 8,500 sites are differentially methylated between sexes at birth, with the differences persisting in to childhood and late adolescence. Whether these observed differences in DNA methylation between sexes are causal to diseases for which differences in prevalence by sex is also observed is currently unknown. We propose to use Mendelian randomization (a causal inference method) to determine if these differences in DNA methylation are potentially causal to a panel of diseases (and traits) which are known to demonstrate differences in prevalence between sexes observationally.