My answer has two parts: At age 11, in an incidental way, with respect to “fixing” tomcats and gelding of horses, done for behavior modification and birth control. And at age 26, in a fascinating, erotically impacting way, with respect to castration of human males for those reasons plus to punish or humiliate them, or to make them into eunuchs as a commodity of value. The topic became a fetish interest pursued ever since.

This human castration awareness began with a chance reading one evening in late 1969 of a paperback copy of a pseudo-documentary on sex and sexual anatomy practices over recent centuries in North Africa and the whole Middle East, plus India, China, and Japan. This book was Cradle of Erotica by R.E.L. Masters, discovered in the deserted lounge of the transient Navy BOQ at the by-then little-used Army and Navy base at Dong Tam in Vietnam, SW of Saigon. I stayed up late reading this intensely arousing text, which catered amazingly well to all my existing genital condition and modification fetishes plus awakening several latent ones which took several more years to fully flower, including fancying myself someday parting with my own testicles and scrotum – for the looks and symbolism rather than to live as an androgen-free eunuch.

Both testicles-only castrations and penis-plus-testicles removals were covered in this book. Intentional making of child and adult eunuchs as servants for sale or as trusted administrative assistants was part of the lore. This was my first encounter with info on cultural customs-encouraged genital modification — all sorts of them, done for both sexual enhancement and sexual deprivation — beyond mere male circumcision. It covered sexual practices and sexual anatomy in both genetic and culturally modified variations, including genital shaving, male and female circumcision including removal of clitoris and small labia, plus castration of boys and men to create eunuch servants and also as triumphant abuse of captives after battles. Of the latter, an example:

[during the 1919-26 revolts in Morocco] “the fanatic Riffs, Berbers, and Kabyles castrated every French and Spanish soldier, wounded or dead, whom they found uncircumcised.”

Once “back in the world” and out of naval service, I promptly bought a copy of my own, in hard cover, and have pursued the topic ever since, eventually discovering BME, EA stories and this forum.

My first exposure to it was probably in an episode of Ren & Stimpy; I didn't quite know what "Mr. Neuter and Mrs. Spay!" were at the time, however, and it would be a while until this crossed my mind again. This time, I was exposed through the furry fandom; in 9th or 10th grade, I discovered that there happened to be porn of it, and went exploring.

Well, I found the art of a guy who went by Salamander back then, and Kouei now. In fact, he's re-hosted the pictures in question, both of a young dragon losing a set and - clearly - enjoying it, and afterwords, healed up, clearly no worse for the wear. (Links are removed, as "banned site" appeared in my post - PM me if you're curious)

I was simultaneously horrified and aroused at the prospect.

I had no plans to have myself so modified, but recently Dexter and Lefty have decided that they're going to start paining me. NSAIDS aren't doing anything, and antibiotics aren't either. I know there's a flowchart for diagnosing orchalgia, and I know where it leads. At some point, I'm going to have to decide which I prefer - pain in the pair at random intervals, or a pain in the ass every week for hormone injections (or every six months, if I go for implants). This has sorta brought the idea back to the front of my mind, and … apparently, it's been gestating back there, and I'm no longer horrified by the thought.

I knew that testicles can be cut off, at age 11. Then at 15 I learned that castrations actually had been done in history and ballless men really existed. Since then i have been thinking about becoming one.

I've been aware of it as far back as I can remember I just didn't know the name for it. When I first heard of castration (other boys making nervious jokes about it at the age of about 10 or 11) I wasn't at all surprised. I always figured it had been going on for some time.

I did not know the word castration however I knew that my testicles did not belong at age 7, I was finally castrated at age 55.

river

Oh shit!

Maybe since I was a teenager. I didn't think about it much, though. Too busy playing with the damned things... I guess...

I believe, so long i can think i was fixed in the desire of modding , nailing and cutting my sextools.

I was aware of castration 2 years ago, I was 24. But I remember tying my testicles when I was 20 or 21, but never knew it could castrate me. Only did it because I wanted to stop masturbating too frequently. Thought testicles were only for sperms production, until I became aware about the Testosterone effect.

I grew up with farm animals. around 8 years old when cutting bulls and banding sheep with my dad and uncle, I asked why and was told so they can't make babies. I later found the elastrator in the tack shed, banded myself and showed my little sister and told her I wasn't going to have babies, my parents were less than pleased, I was taken to a shrink and the elastrator dissapeared.

I was ten or eleven when that same uncle and his sons went on a "hunting trip" and came back sterile. I learned what a vasectomy was then.

My father and I never experienced castration or vasectomy.

As I neared puberty I became aware that I was not very good at being a boy. The only other option I knew was being a girl. I was in my early 20's when I first read a story about a young man having his testicles removed. Wow did that idea cause fear and excitement.