Laura from what I could gather, my dad and his sister, both knew about chastity belts. They are kind of from a "IT" background - my dad was part of handling communications and infra management for the army - so that could be where they know it from. Also, he knows where to get chastity belts made (from the local supplier) that could have played a part too.
I've kind of talked with my cousin, but like my brother, too much of a age difference, the connection with them never felt that I could bring it up - unlike my sister.
I don't know if my aunt is belted (seems unlikely)
Let me know if I answered your question. I have a feeling I probably raised more confusion than clearing it