Hmmm, explain further, because this is what I'm gathering from you speculation:

if,
Y=How old are you?
and,
Y=X
then,
X=How old are you?

So, if someone asked me "How old are you?" you would answer by saying "How old are you?"

Maybe this situation would work if it sounded like this though:
Person A: "How old are you?"
Person B: "How old are you?"

Just a retorical question back at the person, but that is pretty tedious and doesn't really answer anything.

Is that what you meant Chruser, if not, explain further.