estrogen is a human hormone, not a plant hormone.. and even if a man were to talk estrogen pills, he wouldn't turn into a full fledged female.. sure, he might get man boobs and less hair and a higher voice, but he's not going to grow a va jj just because he took some estrogen, same for plants..
if you want guaranteed females, but feminized seeds from a quality breeder and not some hacks like greenhouse seeds or barney's farm, both of whom are known to have issues with their fem'ed gear..
fem'ed seeds are about 98 / 99% guaranteed female offspring, and i've been 100% on all of my fem's thus far with all of the different breeders i have tried including dna, sagarmatha, dinafem, dr greenthumbs, and even cali connection..