when you take a female plant and clone it, then take one of the clones and force it to become male by using a weak water/asprin mix to water it with. that usually works. when it grows a male bud the pollen it contains is "feminized" or has two Y chromisomes when you use this pollen to fertilize a female clone's bud the seeds it produces are feminized, or they grow female, however you want to say it. when you come across a seed in some good kind smoke, save it. more often than not it will be female. but keep in mind that i mean GOOD kind smoke. most of those seeds are accidents. sometimes a female plant becomes hemaphroditic and then produces female male buds that hold that same feminized pollen i spoke about earlier in this response. thus creating feminized seeds in the nug.