Gelded? Eppp? Do they do that to there own?

Ok read your big stuff....

I like it though to be honest Im not sure I buy the castration bit as a likely cultural development. What did they do before they had low risk testicle snips? Once they had it what made it a popular choice for males would not reproduce? Where they just going out and dieing quietly in the past?

Note Im not criticizing, I think its a fascinating centaur culture just wondering on the whys and if you had thought of them yet.

No, I appreciate thoughful questions - lord knows, I'm happy anyone READS nowadays, period LOL
I know it doesn't seem terribly likely, but I'm trying to come at things from a nonhuman perspective. I don't think a human would consider it a good idea, but maybe something with a different psychology would. Then again, many human cultures considered castration normal, and for pretty much the same reason I have here - if you're a eunuch, you're no threat to the guy in power.
Historically, a centaur who had no chance at being a herd husband faced a fairly rough life. Being in the bachelor bands is terribly dangerous, not only because of outside threats, but because intact males are extremely prone to violence. They were dying, but not quietly. On the other hand, a castrato would lose the ability to reproduce, but gain the opportunity to be a peaceful member of society, and - from the selfish gene's point of view - be there to help out his genes as embodied in his sister's children, or brother's children.
Not sure how long this would have been going on, since I haven't worked out how old their culture is. Humans figured out castration (on livestock at least) pretty early on, and the centaurs didn't have any dark ages to slow down medical advancement, so it's probably been going on for quite a while. It's actually not a complex or dangerous procedure if it's done carefully.

Dunno if this is convincing or not. It works for me as a writer, though, there's inherent conflict in a society like that and conflict = plot. :)

I spent a little time looking for information on Eunuchs and wasn't able to find the details I was looking for. I believe historically speaking mothers did this for very young boys who had no chance to live a 'good' life. By gelding them at a young age they could get into positions that otherwise would be closed to them.

In the culture your building here perhaps it started the same way mothers gelding sons who were very young but clearly would never get a position due to birth defect or accident. The problem as I see it and perhaps isn't really a problem depending on how you look at it is that if you geld a horse (I know this is true for horses not sure about other animals) late in life you do not always kill the sex drive. On the other hand you can count on them shooting blanks after that.... Mind I'm not sure what the ratio for those keeping there sex drive in horses is but I do know that if a stallion has breed mares (or ie had sexual relations) its a lot more likely to keep his sex drive even after gelding.

I constantly use this for my centaur drawings, because the human and horse halves are perfectly proportioned. :D