I'm cis. I've been pretty indifferent to norms of masculinity since I was young. I used to wear corsets and makeup and skirts to goth clubs back when I was cool. As a perk of being well over six feet and a man no one ever gave me shit about it, and on the very rare occaisions they did I wasn't impressed. Maybe it's a neurodivergence thing or a bipolar thing, idk, but I never really considered my masculinity, such as it is, something society was worthy to challenge.
I guess some of it was a very bad experience with Texas' unique brand of toxic masculinity and violence when I was a kid. It put me off of a lot of traditional toxic masculinity bonding stuff - football, beer, cops.
And I had probably the weirdest frat experience in college - very supporting, very loving, all for one and one for all, no hazing. Most of the old guard was thrown out for being frat bros the year before I joined so we mostly built the culture from the ground up and it was pretty good. Like this was the bush adminstration and the gay straight alliance would all come to our dry mocktails parties. We barely knew trans people existed but we decided that if someone wanted to join, and asserted they were a man, we could only induct men under the national rules but the rules didn't tell us we needed to check people's genitals so we'd take anyone who said they were a man.
And then, like, hanging out with sex workers and strippers, gave me a lot of perspective on shit women put up with. I got firmly in to feminisms early on, did a lot of reading, hung out with some real cool feminists. Dated a whole lot of queer women who didn't expect normative traditional masculinity from me.
I ended up having mostly queer friends, including a bunch of trans people. Learned a lot, read a lot, talked a lot.
So, i got lucky in a lot of ways. I got turned off to toxic masculinity early. I'm a huge man and that gave me safety to play with gender, have fun. I met a lot of cool weirdos and good people. I had the opportunity to learn a lot. In college i studied anthro, which is studying culture, which is all about breaking down what you think is normal. Had some cool queer professors and cool marxist professors.
Oh, and i guess i was introduced to transhumanism early from reading tons of sci-fi, and radical bodily autonomy, being able to make your body and mind whatever you want whenever you want, once i started to learn about transgender people it was just a natural fit. Like of course people should be able to express whatever gender or no gender, change their body to suit their needs, what feels good and correct. It was completely consistent with transhuman ideals.
So, put it all together, i've had a lot of advantages for exploring, critiquing, and playing with gender, and with all those advantages i ended up cis+