You figure a gender fluid world sounds most fun and would probably have the least differences and complications from the world as it exists now. You're tempted to change the text of the 'Gender' page more, but decide to keep it mostly the same besides making it so gender isn't fixed without outside intervention. After writing up this different version of the page, it reads like this:
"Aside from a tiny proportion of people, humans are born either male (with XY chromosomes) or female (with XX chromosomes) and have a random but just about even chance of being one gender or the other. Around puberty, people develop gender fluidity, and their bodies become able to change into those of the opposite gender and back. Some people identify differently from the gender they're born into, either identifying with the opposite gender or outside of male or female, and once they develop gender fluidity, they will generally shift into a gender they prefer and stay that way."
You hit 'Apply', and feel a shiver run through your body as human genetics alter to fit what you've written, including your own. It's weird, your body feels... malleable now. Like this isn't the only way it can exist. Naturally, as the only person not innately familiar with what this version of the world is like, you start wondering about it, not sure what to do first...