My oldest DD didn't have problems with the whole thing when she figured it out around 11 or so but my youngest DD was totally devastated and couldn't get past the fact that we'd lied to her. We tried to explain that the concept of Santa was just a sort of symbol of the spirit of giving and it was just supposed to be a fun thing but she seemed really upset for a long time (about the deceit and hypocrisy of our teaching that lying is wrong and then pulling out this ludicrous whopper), I think it also started a line of questioning what else we may have lied about or may still be lying about and it stemmed a bit of a mistrust of adults in general. It killed me because I never felt too good about the charade in the first place but I didn't want my kids to miss out on the fun or ruin it for others. She's over it now at 17 (I'm pretty sure). I am curious to see what she does if she has kids.
On another note, I was glad when they finally did figure it out though because it really started to get hard to stay awake later than them and I got a bit tired of not getting credit for the toys ;-)
