I, too, believe that my mother's grandfather, Adolf Follmer, was born in Germany and your mention of both Cuxhaven and lighthouse keepers rings a bell. Her father, August A Follmer, was born in NYC in June, 1871. I only know of one brother, George, born in 1870.I think we're looking at different generations. Unfortunately my mother passed away in 1993 and I can't add much to your information.
Since your message is nearly 5 years old, I hope this reaches you. Please keep in touch.