Anxiety doesn't always begin "naturally". Sometimes it is the end result of years of abuse, whether it's mental/emotional or physical. Be gentle with people that have anxiety issues, you never know what their story is.
happens too often. Most of the time I stay quiet because 1. I'm not admitting that I am quiet, because I'm really not, I just don't know you 2. Some unintelligent thing will come out of my mouth if I open it and 3. What's the point in telling them why I'm quiet when they wouldn't understand or care or stick around long enough anyways