It states that having boys/girls is an inherited trait. If your father had lots of boys, chances are that you will too if you are a man. 
 
If the womb is acidic, female sperms wins( stronger yet slower).

Between the unknown factor and the sure deal of waking up to another Bush presidency, I'd rather take the unknown path. All I know is that Obama is not Bush, he speaks different, thinks different. Besides, with an ex-moslem reputation, the moslems might see us differently from enemies of allah to brotherhood of men, then we dont have to send our sons and daughters to war.