Since when do guys (generally) treat girls differently?

I'm ashamed of what I'm about to admit:

In my school years (all the way till 9th grade) I've annoyed some guys. It included stepping on his foot, nearly tripping him by sticking my foot on purpose, grabbing his bottom and throwing water on his desk and shirt. Some didn't care and a couple of them had a ''not this again'' looks and one actually complained to my mother and a teacher.

In comparison, my younger brother already has gotten into a couple fights but much less. During an argument, he insulted another guy's mother and it immediately led to a fight. Neither of them won. It was even.

Perhaps I'm older already (26 years old) and it was a slightly different time. But since when do guys (generally) treat us differently? All of the above I did would've been enough to start a fight or get strike.
Updates
+1 y
I'm also guilty of doing what my brother did (during an argument tell a jerk in anger ''I would pee on your stupid mother's grave'') and he left, kicking the an empty soda can saying on the ground, saying ''biotch'' over and over again.
Since when do guys (generally) treat girls differently?
Post Opinion