I mean, my lifetime experience is one of "being different". I was fundamentally different from my classmates since day 1. Teachers picked up on it immediately and were concerned that, while I breezed through everything and seemed to be very "sharp" (or whatever funny word they would use), I was totally disinterested and seemed bored and unhappy. I was. I learned nearly everything I was shown instantly, and usually understood it effortlessly. In grade 3 I excelled so strongly at spelling that the teacher had me make the weekly spelling tests. In grade 5 I was the only kid who actually copied down and memorized "pneumonoultramicroscopicsilicovolcanoconiosis" and "phthatlylsulfithiazole" when the teacher wrote them on the board to be funny (though he spelled them wrong at the time, I later learned). FWIW I just typed those from memory without checking their spelling.

Environment surely does play some part. I grew up in a home that fostered intellect, learning, growth etc. I'm sure there are countless studies on "nature vs. nurture" and my subjective view is both are relevant, perhaps even fairly 50/50. But my life growing up I was the exception to the norm in all environments. I have some really stark examples that could really hit this home but I'm not going to post them on here, but... there's a lot of truth to the "differentness of giftedness".