Okay I always hold a very particular standpoint on this type of question. Tell him the minute he asks any questions. I can tell you, as I was growing up, I always knew about my CF. When parents on the board have asked this type of question before, I've tried to sit down and think of when my parents told me. For the life of me, I cannot come up with it. I've known since before I can remember. I cannot pinpoint my knowledge of my CF to "the day!" (dun <u>dun</u> <u>DUN</u>) when my parents told me, because I've never known anything else. My parents were always very open and honest with me about it. I was a poster child for a few years around age 6. I know most people think little kids can't handle such a big issue, but you might be surprised. If you put it off too much longer, it's just going to become harder to tell him anyhow. I think you should take a cue from his questions. If he wants to know, tell him. I mean obviously, you need to use different words and phrases to explain it to a 5 year old, but I really think you should take his curiosity as a hint.
I also know a lot of other parents will tell you to wait. He's only 5, he won't understand. But in complete honesty, I cannot remember the day my parents told me. I've just always known it. And I'll be the last person to "toot my own horn" so to speak, but I've been told by many family members, friends, loved ones, teachers, etc in my life that I'm a very strong person. Of course I have my problems, as everyone does. But in general I think I came out pretty cool. I attribute that highly to my parents and the CF itself. It's made me a stronger, kinder, more compassionate and understanding person than I would've been without it. I've gone a little off track here, but basically my point is, I came out as a pretty "well-rounded" adult, and I have always always known about the CF.
If Zach is asking about it, he wants to know, and I think you should tell him. It is, afterall, within his own body and I think he has a right to know. Especially since he's asking about it.
Mind you, I didn't mean for any of this to come off as rude, so if it did, I'm sorry. I just tend to be rather opinionated (heh), and I think I have pretty good reasoning and back-up to do so. But you asked for people's take on it, and this is mine. <img src="i/expressions/rose.gif" border="0">