Chances for Male/Female

Why is it a 50-50 chance that a baby will be a boy/girl rather than something else, like 55-45, etc.?

>>40
You forgot to add >>36 in same fag.

Gophers = Jail sentence

>>38
notice BIRTH ratio, have you considered that many people might abort a girl and not a boy?

China doesn't help with the 'Lol girls suck, abort abort' thought.

There are two levels at which to look at this problem.

Purely statistically, the mother donates one of two X chromosomes while the father donates either a X or Y chromosome. This second one determines the gender. It should be obvious why there is a 50/50 chance here.

Biologically, I'm pretty sure that chromosomes have no effect on the sperm cell carrying them, but it's quite possible that those carrying Y chromosomes are lighter, especially since Y chromosomes are much smaller than X chromosomes (http://home.planet.nl/~gkorthof/images/XYchrom.jpg). I have no idea what other mechanisms affect the chance of selection at this level.

Purely statistically, the mother donates one of two X chromosomes while the father donates either a X or Y chromosome. This second one determines the gender. It should be obvious why there is a 50/50 chance here.
If you go about it naively, sure. However, it's been pointed out already that this is a retarded way of looking at things.