A lot of what Palpatine told Anakin could have been a pack of lies with a tiny grain of truth. This is the guy who told him he killed Padme after all. Not to mention implying he knew how to cheat death, and when Anakin has taken the bait, Palpy is all “well, I’m sure we can learn how to do it”.
I’ll bet that bastard never even brought it up again.
Why would Palpatine lie about Plagueis’s gender?