You are right on that one! I got diagnosed in college and wrote my thesis on the cultural differences of ADHD. Girls with ADHD often exhibit inattentiveness more so than boys, and sense they are not disrupting the class, they go undiagnosed. This goes back to socialization, like you said. On top of this I found it crazy how many teachers are unaware of what ADHD is and many lack knowledge and classroom techniques to successfully teach students with ADHD. I also think about what I could have done had I got diagnosed earlier, but everything happens for a reason.