My parents told me -- I don't remember how -- but they must have been pretty low key about it (I'm making this up but I can imagine what my dad would have said: "You scored X. That means you're very smart. But what's important is that you be a good person, always do your best, and learn more than is required of you" -- so, de-emphasizing the meaning of the test, and emphasizing what he thought was important.)

It was a non-issue for me growing up; IQ scores just never came up in conversation... that is, until I was in college and my boy friend shared his IQ, which was in the gifted range, but, uh, not close to mine. I didn't say anything about it to him, but I found it both obnoxious and a little sad (not his score, but that he should brag about it so).