Ticklish - I have to disagree with you there.. For sperm to form it splits into two from a parent sperm. This parent cell is an XY cell so when it splits to form a sperm cell it forms one X sperm and one Y sperm. From what I have read it's the environment of the female vaginal tract that dictates which gender survive better than the other through to the uterus.. Acidic or alkaline conditions.. And so a female diet subsequently can help alter the vaginal pH to favour a certain gender surviving over the other.

I still believe it's mostly luck though..