i'm another one who grew up being made to feel different and wrong for liking things that weren't considered typical of my gender--at least once i passed a certain age.
when i was a little kid, playing with bugs and dinosaurs was the norm. i guess, looking back, me doing "boy things" was accepted because i still seemed to like "girl things". as long as i wore dresses to sunday school and played with barbie dolls (nobody had to know i was actually just feeding them to the plastic shark), no one batted an eye if i wanted to wrestle my cousins or play in the mud. being told that something was for boys was confusing, but for the most part it didn't come up often and i didn't give it much thought. when the boys and girls got separate party favors at my birthday, we all just ended up trading with each other anyway. i wanted cats and dinosaurs. i got cats and dinosaurs one way or another, so i was happy. i usually liked the girl stuff i was given anyway, and was too polite to ask for anything different. i still got bugs and science, and if i didn't get what i wanted, i had some male friends and relatives whose things i could play with just as well.
and i guess those were things i did take for granted, because i was pretty baffled when, from "preteen" onward, everything was all about how i wasn't feminine enough. i couldn't wear baggy clothes. i had to start wearing makeup and plucking my eyebrows. i couldn't slouch. nothing was ever pretty enough, and i was always having things like body spray and lip gloss and pink clothes (even so i constantly complained that i hated pink) being shoved on me. and it was then that i realized just how much of the stuff i like was "boy stuff" and not just "everyone stuff"--at least from my family's point of view, anyway.
i'd love to give input on whether or not i ever thought everyone wanted to be the opposite gender, but i don't think i ever really considered that at all beyond "i'm sure everyone would try it for a day if they could, just to see what it's like". i tended to assume most people wouldn't want to be stuck that way permanently, and for a very long time i tried to convince myself that neither would i.