Gene of the month - Ken and Barbie

Our gene of the month is Ken and Barbie - yes, named after the dolls. Like their plastic childhood counterparts, male and female flies with a fault in the gene have no external genitals - their naughty bits start to develop but get stuck inside the body.

The Ken and Barbie gene itself encodes the instructions to make a transcriptional repressor - a protein that prevents genes being switched on. Ken - as it's usually known - sits on genes involved in making a fly's genitals and keeps them switched off until the precise moment they're needed.

Luckily for us, there's no human equivalent of Ken and Barbie, although it's distantly related to a gene called Bcl6, which is involved in lymphoma.