[yaddayadda]

Biological sex is many things, chromosomes, genitalia, hormones, and the effects of these. If any of these don't match, is the person a guy or a girl? Even among these, there is ambiguity. I have a friend who - no joking - was born with both a vagina and penis. According to you, is my friend a guy or a girl? There were Olympic athletes who had vaginas and no penis but XY chromosomes, are they guys or girls? There is at least one study that showed transgender women (regardless of transition status) had traditionally female brains, so why should a penis at birth be more important then the person's brain?

[jlgreco]

I understand how people could be not aware of this (most children's books don't cover the subject after all) and I can understand why it might make some people uncomfortable (although it does not make me uncomfortable, unfamilar things of can make people uncomfortable. I get that.)

What I, for the life of me, cannot understand is why someone, after being informed of it, would reject the notion entirely. Where does that come from? How does someone ascribe so much importance to the concept of a gender/sex binary? Just imagine if people reacted the same to the concept of political ideologies neither republican nor democrat... I cannot fathom it, nor any reason for it.

[yaddayadda]

I think some of it is background, some of it is knowledge, some of it is time to acclimate to new knowledge, and some is Cognitive Inflexibility (https://eslkevin.wordpress.com/2012/06/23/why-conservative-f... and http://mprcenter.org/blog/2008/11/06/media-framing-conservat... ).