I've just read an ancient Mayan ritual for predicting the sex of your baby:
If the mother's age at conception and the year of conception both end in either an even or an odd number, then baby will be a girl.
If the mother's age at conception and the year of conception differ in terms of oddness/evenness then baby is a boy.
This method is accurate for my 2 DDs, so so far is 200% accurate
It predicts another girl for me! Have my 22 wk scan tomorrow, but DH insists we don't find out the sex this time, so I have to rely on methods such as this.