WHat natural conditions amd nutrients tend to produce more female plants from seed?

Are there any natural conditions that are more favorable to producing female plants from seed? I have heard that more acidic soil tends to produce males and that better ph balanced soil tends to produce more females, and that generally better growing conditions all around will produce more females on an average - however I don't know if that is just a myth. Are the sex characteristics already pre-determinded before it is planted or are the male and female hormones induced when you switch the light cycle, and the quality of the plants will decide the sex?

Think about this one....its all genetics. All of the genes are already there, in the seed so....

well, marijuana seems to be a plant that is able to choose it's sex and also hermaphrodite, even plants with "good genetics" so thats why I asked the question. Plants that have been feminized are obviously a different story.