When you were a kid, how did you learn the difference between circumcised and non-circumcised boys?

Meaning learning about uncircumcised penises if all you've seen are circumcised ones and vice versa. How did you find out and how did you react?

Unlike most other American girls (especially those in my town, which by being a upper-class southern east-coast neighborhood that was almost entirely white, had a circumcision rate close to 100%), my brother's penis was uncircumcised. My mom was very liberal and hippie-esque (obviously, she clashed with our neighborhood) so she opted out of having my little brother (1.5 years younger than me) circumcised.

Because we were so close in age, we took bathed together until I was in 1st grade and he was in Kindergarten. We also "played doctor" constantly around the same time we stopped bathing together. Because of this, I had become very familiar with his penis and I assumed that was what a boy was supposed to look like and that all the boys in my class resembled him below the belt. When he was in 3rd grade (I was in 4th), our pediatrician was concerned he couldn't retract his foreskin yet and she told my mom to take him to a urologist, who gave my mom a cream to put on his foreskin every night to loosen it.

One night, my mom caught me trying to sneak a peek when she was putting the cream on my brother (at this point, all I knew was that there was something wrong with his privates). Instead of being mad, she told me to come into the bathroom and watch (she didn't believe in kids, especially boys, having modesty) and explained to me that the skin was tighter than it was supposed to be and it had to be loosened with the cream or he would have to go to the doctor and get it cut off. For the next three years, I thought of the foreskin as something like an appendix, where every boy had one, but on the off chance something bad happens, it gets removed.

One night in 7th grade, I was sleeping over at my best friend's house, helping her babysit her baby brother, and this included giving him a bath. When I noticed he didn't have any skin on his penis, I asked my friend why and when her brother got his foreskin cut off. She was obviously very confused, and told me that he's always looked like this.

When her mom came home the next morning, we asked her about it and she explained circumcision, along with it's benefits and it's prevalence in America. The next day in school, me and my friend asked all of the girls in our friend group who had brothers whether her brother's penis looked more like a " mushroom" or a "crayola crayon". Every girl said mushroom.

Does anybody have a similar experience going either way (seeing cut as normal and learning about uncut or vice versa)?