Think that certain types of people are drawn to people like yourself OKrad. It's not so much that you don't talk and seem shy, although that might be part of it. It might be your demeanor, it also might be that you are female, look younger than you actually are. People tend toward treating some females as not terribly bright, as if they were only what appears on the outside. They are the same ones who judge others on appearance.
Also look younger than I am. By about ten years. And it used to happen to me quite a bit. It got to the point that I began letting grey hair show, so that people would be a bit more respectful.
Have a kind of 'excited' personality, that seems to appear childish to some people. It's more that I become excited by ideas and their potential, rather than trying to draw attention to myself.
Used to have this group of friends, we all did things together, and one day we all decided that we would have IQ tests for the fun of it. There were three people in the group whose parents were uni profs, so everyone assumed they would do the best on the IQ tests. These three were the core intellectuals of the group, they were the ultimate authorities on things. When the results came back, I could still see the looks of disbelief on the three faces. Scored so much higher than they did,
and they used to tease me at times, when I didn't understand something.