We are more common than many thing. However, we also tend to self select our groupings. We are a lot less common than WE feel we are.

Basically, about 50% of my local makerspace are ND. That is way higher than the general populous. However, even within family, work, or random friend groups, I still see an abnormally high percentage. I basically self select for weird people and have done all my life. This seems to be common for many of us.