The research group of Dr Claudia Keller Valsecchi (Institute of Molecular Biology, Mainz, Germany) and their collaborators have discovered the master regulator responsible for balancing the expression of X chromosome genes between males and females in the malaria mosquito. This discovery helps scientists to better understand the evolution of the epigenetic mechanisms responsible for equalising gene expression between the sexes. The findings may contribute to the development of new ways to prevent the spread of malaria.