A recent paper published by Kimchi, Xu, and Dulac in Nature describes the emergence of male-type sexual behavior in female mice following incapacitation of the accessory olfactory system. The authors argue that this implies a default male-type behavioral pattern that is otherwise constantly inhibited in the female brain by chemical signals transduced in the accessory olfactory system. In addition to reviewing these findings, we suggest in this Preview how these findings in the mouse could have relevance for human behavior.