Sex is pervasive in nature. Yet, despite its importance for species maintenance and evolution, sex is unnecessary for the survival of the individual, it can have a negative impact on fitness and is performed by most species (except our own) without awareness of its consequences: fertilization. A myriad of mechanisms has evolved to promote its fruitful execution, such that sex it promoted when fertilization is most likely to occur and inhibited otherwise. In this review we present recent advances in our knowledge of the neuronal circuits underlying sexual behaviour. We discuss flies, rats and mice to underline the breadth of existing neuronal strategies used to accomplish the appropriate execution of this behaviour, while still highlighting shared principles across such distinct taxa.