How is what a transgender person asks us to accept (that they are born one sex, but they "are" the other sex based on how they feel) not the same as me claiming I'm Napoleon? You might say, "But we can factually prove that Napoleon is dead, so that proves you aren't Napoleon." And we can factually prove that someone is biologically the sex they are born (their DNA cannot be changed, regardless of hormones and surgeries). Reality isn't determined by feelings.