You may as well state your gender also, since I’m curious if girls and boys are different in this regard.
I’m male, and around age 14 (20 years ago) I pieced together that others must do it also when some kids called another one a “Jerk-Off” or implied that he was caught doing it. As a teen or in college, I don’t think I ever discussed masturbation with another guy since it seems like it would be a “gay” conversation (no offense intended). Guys just didn’t talk about it to each other. I’ve talked about it with my wife plenty of times and some girlfriends in the past.
Anyhow, at what age did you realize you were not alone and what is your gender (did girls share info)?