As _delirium said it's probably a language/culture thing. If you were to ask an Englishman "how do you do?" the culturally acceptable thing to say, is "how do y

As _delirium said it's probably a language/culture thing. If you were to ask an Englishman "how do you do?" the culturally acceptable thing to say, is "how do you do?" back or just to signal with e.g. a small nod that you acknowledge the greeting. And it really is just a greeting, not an actual thing someone is asking you. (Unfortunately this carries over to all sorts of social interactions/situations that I'm not conscious/aware of, but this is one that I'm pretty sure about.)