I am very ashamed to say that it never dawned on me at all that there was any problem with how young people were dealt with, until I had left.
I never had the extreme experiences that many on this thread have recalled, I can't imagine how awful it must be to get that from the people who are supposed to love you more than anyone. I can remember specific instances of being smacked, so I don't think it happened often.
However, when I was growing up as a JW, I did think it was perfectly reasonable behaviour to hit a little child because they couldn't sit quietly for two hours. Warped. I am so glad that I never had kids as a JW.
There is one thing about my teenage years - I developed the habit of picking my nails so badly that I had torn my thumbnails right off. I kept the habit up for ten years. My thumbnails are deformed to this day. A quiet little form of self harm. No-one ever wondered what was wrong with me. I wish someone at school had taken some notice, but then, I was so brainwashed, what could they have done?