Well, there are actually people that don't enjoy certain foods that others find delectable. I hate lamb. My father loves lamb. No....lamb chops, roasts, etc. Damn....food never makes for a safe analogy!!

Anyway, the point is that there really is no accounting for likes and dislikes. Much of the time, I suspect that the difference is far more in the mind than it is in the anatomy. I've had my share of anal sex where I was less than crazy about the experience. Yet, with the right guy at the right time, I recall wanting the experience to last forever, and to get as much of the guy's weapon in me as possible. Sorry, not trying to write porn! But I think the point is made: there's no requirement, even if you like guys, to like getting poked in the stern. There are more than enough guys that really do like that, and prefer it, to make up for it.
As to what started fisting? Well, that's a good one. I suspect it goes waaaay back.
There's that size thing some guys have. They just love a well equipped dude. Homosexuality is not a new thing, it's just new that it's verging closer to mainstream, and to some semblance of acceptance. So I don't think it odd to speculate that waaay back, perhaps in the Roman Empire even, some queenie dude wild for cock got innovative and managed to convince his boyfriend to try something new.
Sexual exploration is a lot of fun, let me tell you. Being repressed helps a lot, as does being a social coward (no one in my life knows I'm gay). The kinks I've explored would make some guys that like fisting turn white as ghosts. Some MD's would probably suggest I be admitted for a psych eval! But then again, I read about the ideas behind my "experiments" elsewhere first, and fantasy took care of the rest of the urge. So far, I haven't found anything on this site that really goes too far beyond the pale - except of course the scat and piss stuff. Like those that are horridly turned off by fisting, I can't get my head into scat. Piss...well, maybe. I have a fantasy there that I first encountered on RedRight that I'm dying to try with the right kinky guy.
But I digress. I guess all I'm trying to say is go with the flow...and if one's flow is to never bottom and always top, so be it. As long as no one is hurt, there are myriad other ways to float the boat. Water is simply so pedestrian.
