More specifically, key sex-determining genes (genes known to cause sex disorders when disrupted) such as the testis-determining genes Sox9, Fgf9 and Dmrt1 and the ovary-determining genes Wnt4, Rspo1 and Foxl2 have high enrichment levels of both chromatin marks at the bipotential stage (>log 2.5 enrichment normalized to total H3). This evidence concerns the gene FGF9 and physiological sexual disorder.