To other IPs out there: How have you explained your child's birth story to them?

Today as I was sitting on hold on the phone for my veterinarian's office, an ad for an NPR radio interview began playing instead of the normal elevator music. It was for a discussion about the "modern family" and how it's now created using surrogates, donors, etc. Well, OF COURSE my ears perked up and I HAD to listen to it!! Ultimately the main topic of the broadcast was how do we inform our kids about their genetics if we had to use a sperm/egg donor? Or tell them about the surrogate mother that carried them for 9 months? Or if they were adopted, their birth family?

It's something I'd already given a little bit of thought to, but not sure I had an answer for, especially as it relates to our egg donor. Even after listening to three sets of parents chatting during this interview, I still don't think I have a complete answer. So I thought I'd ask here to see if anyone had stories to share.

First, I want to say that we plan on being honest and forthright early on so it never turns into an identity crisis later. But still, I wonder about how (and when) to tell our future child about the fact that we had to use an egg donor and that they're not "biologically" connected to me. Will they wonder or fantasize about meeting that person? Will they wonder about their genetic history? After all, I enjoyed doing my own family tree on ancestry.com!! (And our egg donor was anonymous, of course.)

Anyways...I'm sure many of you other intended parents out there that have forged this path ahead of us have some great stories to share! Or books that you've read to your kids, etc. So please do share your insight and thoughts!!