Chinese calendar gender prediction

Recently my wife and I found out that she's pregnant. Even though it is early and I don't want to get my hopes up just yet, I can't help but get excited. So lately I'm looking at these gender predictions for fun and I understand that the scientific approach is 50/50, but this one site has been pretty darn accurate with almost all the births I've put in it (Siblings, relatives, and friends). Out of 22 people I've put in it, only 3 came out wrong, that's 86% success rate

I personally don't care if it's a boy or a girl so long as they're healthy, I just find it fascinating and was wondering what the census was like out there. I've made a poll and the link to the site is this:

http://www.baby2see.com/gender/prediction.html