Complete rubbish, besides...65% of statistics are made up anyway

I've already told my OH its all his fault if we dont have the boy he wants, he provided the sperm, I've provided my half of the DNA!

They used to think that if you ate acidic food you ended up with one gender and alkaline an other (can't remember which is which). I think the theory was that your CM was more hostile/welcoming to certain types of sperm...

I think they just guess at these things.