This is just a guess! I would say no. I think when they mean Fem seeds there is a still a chance, 1 and 100 so they say probably more like 10 and 100 ... That you might end up with a male. I think they look at the seed size and weight to tell it's possible sex outcome. I could be wrong cause I don't really know hopefully someone more knowledgeable then me can chime in. So, to answer you question every plant produces fems and males... the trick is to figure out what seeds are females.
As far as i know (well i know this for truth with some seedbanks - but it may not be how all of them do it) seedbanks take 100% females, and apply a chemical to them so they create male flowers, then use the pollen of these to pollinate the other females, this produces seeds which are a very high percentage female. These can however still turn out to be male (very low percentage) or hermaphrodites, its usually down to stressing the plant if it turns out to be hermie though as far as i know. Also as far as i know feminised plants pollinated do not create feminised seeds (unless done correctly by the above method or others that are probably out there - i hear using pollen from a hermie on the same plant usually creates female seeds, the method above though is not actually a hermie) Hope this helps and am willing to defer to some1 more knowledgable than i
instead of making a new thread i thought i would sort jack this one. I got some femm seeds from a site. I believe they are from nirvain so its a good compony. But I have been reading that fem seeds have a high change of turning hermi but it is monstly base don genetics??? I don't know, but should I have to worry about hermis in my fem seeds? I dident think so because its from Nirvania and I believe thats a quality brand.