now days they have seeds that are auto flower or feminized seeds meaning that they are going to be female due to new age research, if you were to look at a reg bag seed there would be no way to tell if it is a male or female, unless it is feminized...hope this helped
It seems like the seed may contain the material it needs to be either sex. During germination is probably when it's final sex is more determined- not when it's still a seed.
I say this because there is some evidence to say that different germinating conditions favor different sex. Dutch Passion made some recommendations years ago such as temperature and humidity which seem to play a small role.
Also, there are products you can buy which will push up the likelihood of a seed growing into a female plant. At my local hydro store they sell a seed soak. You simply soak the seed in the chemical and then germinate it and it greatly increases the chance of it growing into a female plant.