I am trying to think of the scientific stuff I've heard . I think they call it the x and y chromosome , let's say the y is for female , they said something like there is far more y than x so it increases the likely hood of female over male at the time of conception.
The 3 month pregnancy is just a theory I've been toying around with ( don't anyone panic here) lol . who the hell knows for sure what things were like prior to written history .
I just find it hard to believe in these ice age theories myself .