Iron deficiency can cause male-to-female embryo sex reversal. Testis formation is initiated by epigenetic derepression of the Sry gene at a specific time of embryo development. Sry derepression is mediated by an iron-dependent histone demethylase KDM3A. Okashita et al demonstrated that iron deficiency in embryonic gonads decreases the ability of KDM3A to remove repressive histone marks from the Sry locus, reducing expression of Sry in those cells, and causing some XY embryos to develop ovaries.