Origin of the word "Yankee"

My grandparents name was Yanke. One ‘e’ at at the end of the name. My grandfather was of northern German origin, from Breslau, in what is now part of Poland. I offer this as a point of information, no more.

Link to the column in question: What is the origin of the word "Yankee"? - The Straight Dope

As least, I assume that’s the column you’re commenting on? If not, let me know and I’ll provide a correct link.

As I understand it Janke is most probably a diminutive of Jan (=John).