{Reference Type}: Journal Article {Title}: When structure meets function. {Author}: Signor SA; {Journal}: Elife {Volume}: 8 {Issue}: 0 {Year}: 10 2019 15 {Factor}: 8.713 {DOI}: 10.7554/eLife.51746 {Abstract}: A new study upturns the long-held belief that the yellow gene determines sex-specific behaviors in fruit flies by acting in the brain.