I agree that they are fun and not 100% accurate , however I tend to some what believe this one as I have almost proved this one by comparing my ultrasound with my cousin's ultrasound (which has been confirmed boy) and you can see as clear as day what the theory is to display xx
I think those are fun in the meantime till you wait for the confirmation of the gender around 16 to 20 weeks. With all of my kids I did things like pee on soda or Chinese gender calendar. All the things I did were saying that I'd have boys buti never once had a boy. I'm now pregnant with my 5th girl lol all my kids are girls but they're blessings