Honesty, I remember having anxiety before kindergarten. I remember not answering any questions at school because I was afraid of giving the wrong answer and fearing the others kids and teachers laughing at me or thinking I was stupid.
Things weren't bad until probably 6th grade though, and much worse when my parents separated in high school.
I always had a bit of it growing up. I had a speech impediment and I was used to others speaking on my behalf, so I never learned how to speak up for myself. It started getting worse past Grade 3 where I would never participate in answering questions in school, much like NoSocialButterfly. Then it really got bad during my third year of university, which I still have yet to complete after dropping out several times.
It was an over the time kind of thing - I grew up believing I was stupid and this was reinforced by my dad and teachers - over time I have grown to believe that my opinion or whatever I have to say is not worthy, is wrong, stupid or will sound idiotic - I used to get physical and verbally abused in school and at home as I was slow due to unknown dyslexia.
Emotionally/verbally abusive parents. When you're told every freakin day you're not good enough at anything you do and that you get in trouble for everything and all the littlest things... I guess you just become that way when you're older. To this day I still have bits of trouble trying to calm myself down and telling myself I am not doing anything wrong. Yet I still often feel I am doing something wrong. "Darn, I shouldn't have asked them to hang out." "Shoot, I shouldn't have posted that status even though I didn't say anything wrong or offensive or whatever." "Crap, what was I thinking.. why did I ask them that Q?" "Dang it, I could have done a much better job. I did great but still not great enough. I'm a failure now."
I set such high expectations on myself.. just like my parents did, do, and always will. I'm working on gradually "letting go" and sometimes it works well, but some days I treat myself so badly, it's a disaster.
I was in 5th grade and the teacher made us do a presentation. It was supposed to be like a commercial for a made up product. I, of course, was not prepared so I half assed something together at the last minute. That wasn't the bad part, the bad part was the teacher recorded it and before recording it he talked about how he was going to show his students next year. That was the first memory I have of ever being anxious, and it seemed like from there my life took a crappy, anxiety filled turn.
It's a combination of things for me. When I was 4 and my little brother was 2, he got really sick and had to go to the hospital. It was a huge change of routine for me. Before my brother got sick, my mom would babysit the neighborhood kids, many of them my friends. She no longer had the time to do this when my brother was sick, so i no longer saw many kids my age. We spent a lot of time in the hospital around that time. This was traumatic for me and might have contributed to my anxiety. Around this time, I developed selevtive mutism, which may have later lead to anxiety. Also, I've always been a quiet person with a calm temperament, that's a risk factor for anxiety.