That one is not a technology one indeed. I intermingle some non-tech ones just to show that there are curious simple things everywhere, and that there's more than just tech in their lives.
I don't think you can truly answer that question without it being part lie. For one, we don't necessarily know the real reason, plus there's multiple reasons anyways, especially since it's taken on a life of its own and culture/history is part of it now.
What's more interesting than the answer to that question is the question itself. People live that way, taking it as granted, without ever asking. Merely putting the question before them is illuminating for them. In terms of actually asnwering, I do not have to go beyond what you have said, "it's taken on a life of its own ... part of it now", though I am prepared to dwell more into the history.
Btw, the students find that question a lot more exciting than the others. Perhaps talking about the opposite sex is subconsciously more appealing to them, especially at that age.
Does technology have an answer for this?