Malaria is caused by a eukaryotic microbe of the Plasmodium genus, and is responsible for more deaths than all other parasitic diseases combined. In order to transmit from the human host to the mosquito vector, the parasite has to differentiate to its sexual stage, referred to as the gametocyte stage. Unlike primary sex determination in mammals, which occurs at the chromosome level, it is not known what causes this unicellular parasite to form males and females. New research at Stockholm University has implemented high-resolution genomic tools to map the global repertoire of genes of gametocyte development towards the male or the female sexual fates.