Personally, I’m skeptical of the claim that “these guys were dominated by women from an early age, so they eroticized their pain and turned it into pleasure.” That’s one possible explanation, but it could also be pure coincidence. We’re not hearing from all the guys who were dominated by women and DIDN’T develop a size kink, so we don’t really have any group we can use for comparison. I think most men who had these unpleasant childhood experiences probably wouldn’t be very forthcoming about it when talking with strangers or acquaintances…UNLESS they were trying to come up with a possible explanation for why they developed an unusual fixation. Searching for answers to that question might cause you to go to places where you wouldn’t otherwise go.
My mom was very domineering and controlling (and still is), and my sister took after my mom. As a kid, I was frequently dominated by both of them to varying degrees, even though my sister was two years younger than I was. I hated every second of it. I didn’t develop an interest in giantesses or being dominated. To this day, the thought of being dominated or degraded by a woman is a MASSIVE turn-off for me. Instead of being interested in giantesses, I had an interest in protecting tiny women (I’m definitely not a switch). I think I had this interest by the time I was six, if not younger, and I don’t remember it being triggered by a particular event or a particular piece of media.
Anyway, my childhood experience was somewhat similar to the experiences reported by these male GTS fans, and my interests went in completely the opposite direction, compared to theirs. I realize that I’m a minority in the size community, though. I also realize that my experience could be an exception, and exceptions don’t necessarily disprove the theory.