Going off topic.... but it's just family tradition usually to choose what you are called. My family were always nanny or nanna; others gran / grandma; and because I grew up after the war, in an area with lots of 'immigrants' there were Italian, Polish, Czech variations as well.
I didn't think much about it until my very good friend was expecting her first child, and we were in conversation with her mother, who announced haughtily ' Nanny is either a goat or a person employed to care for children. I am neither'. She said this just after my own beloved nanny died, and I felt quite upset! But then I realised there was a slight class distinction, which may be what jackthelad means!
Anyway - huge thanks to all you grandparents keeping this show on the road, whatever you are called!