Well, that was quick!

I have discovered one of my 10 times great grandfathers.  The Tinsley family, of whom my paternal grandmother was a member, and who apparently came from Ireland, married into the 'Schwitzer' family in the late 1700s.  My great-great-great-great grandfather Thomas Tinsley married Juliana Schwitzer.  Juliana's grandfather, Johann Christoph Schweitzer was born in Assenheim, Germany in 1685.  He moved to Ireland in the early 1700s and married an Irish woman.  His son, John Schwitzer (the surname got changed) married Mary Shier.  So Juliana was a Schwitzer and was one quarter German.

The Schweitzer family is traced back as far as my 10 times great-grandfather, Engelhardt Schweitzer Setzer 1551-1612.  His parents are unknown, so that's as far back as I can get.  

My Maths isn't the best, but if the German blood dilutes by half in each generation I would be 1/256th German!  So not much really....

I will be interested to try to find out exactly who my German relatives were though in their society.