Low iron levels can flip the genetic switch on a mouse's sex during development, causing XY embryos to grow female features.

In mice, a lack of maternal iron impairs an iron-dependent enzyme that activates the male sex-determining gene, causing some XY embryos to develop ovaries.

The team observed a reduction in the proportion of female somatic cells by overexpressing Sry in XY embryos of iron-deficient mice. However, when the team replicated maternal iron deficiency through ...