I had been lead to believe early on that touching your private part for any other purpose besides peeing was bad and bad for you. Before I even knew what masturbation was or really understood the connotations behind touching one's self, my Mother had inoculated me against such behaviors. Countless times she'd tell me that my body was private and should be kept private at all times and that I should never touch my penis unless I was using the restroom.
Nevertheless I believe that hormones and instinct overwhelmed the guilt that my Mother tried to instill in me. When I was 12 or so things started getting very interesting "down there", hair was growing, my testicles were getting bigger, my penis had increased in size and was becoming erect more and more often for seemingly no reason. I was beginning to develop a curiosity about my body and the bodies of others. I tried to imagine my friends going through the same thing I was going through. I was always peeping at whoever stood next to me at the urinals just to try to see where they were in comparison to me. I found that there were many different sizes and shapes of penis on other people who were my same age and this made me even more confused about my own growth and development.
One night I was laying in my bed and I couldn't sleep... http://firstexperiences1st.blogspot.com/2009/06/first-experience-jacking-off-not-so.html