I don't think it was a made up story of your Grandma. I think our families do lay down certain symbols and myths when we are younger that we find as we gain out capacities have a larger connection to the outside world and we flesh them out.

I also find it interesting how much mystical literature the Church holds onto quietly. A lot of the seemingly mystical hand gestures and such that I do on a daily basis or nothing more than making the sign of the cross over my food myself or others and yet when I do it in front of others I realize that yes...actually it probably looks like magic haha.