The Johann Gimbel Family Home Page

I am researching the Johann Gimbel Family. Johann was born November 26, 1857 and came to the United States about 1884-5 from Germany (Marburg). His passport was issued in Königreich, Preussen. He married Anna Augusta Brandenstein in Philadelphia (Olney) PA on May 11, 1886. She was from Connecticut. I think Johann had 3 brothers and 3 sisters but that only one brother, Henry and one sister, Sophia, came to the United States.
I am in search of Johann Gimbel's parents who remained in Germany. If you have any tips on how to research Germany statistics, please let me hear from you.