Robotic assistants: why are so many robots female?

With the rise of automated personal assistants -- Alexa, Cortana, and countless others -- developers are faced with a big question: just how'human' should these robotic people be? The more human we make them, the more important it seems to give them names, personality and -- more worryingly -- gender. But robotic assistants don't have gender. Strip them of the names and voices added by their human creators, there's nothing there that requires a chat bot to be'he' or'she', other than our own assumptions. Yet still many chat bots have names, and a disproportionate number of them are sold to us as'female.'